It is not the strongest of the species who survives nor the most intelligent that survives. It is the one that is the most adaptable to change.

—Charles Darwin

You're waiting for the elevator on the 10th floor of an office building when the fire alarm blares. Then a security announcement orders you to immediately evacuate the building, avoid the elevators and use the stairs.

Panicked, you rush to the stairwell and run down the steps. Near the fifth floor, a guard stops you and says the lower levels are blocked. You must find your way to the 30th-floor rooftop, where you will be helicoptered to safety. Terrified, you join a growing crowd of people pushing and shoving their way to the top, clinging to hand rails, some stopping to catch their breath, others collapsing, while a few race ahead.

You crawl under caving walls and hop over fallen debris. Finally, gasping for air, your knees and legs aching, and trembling from terror, you kick open the doors to the roof, run to the chopper and collapse in your seat.

You survived.

Six average people who enacted this scenario were cast for the first segment of Could You Survive?, a Discovery Health TV series I hosted based on my book Fit to Live (Rodale 2007). On the first go–around, none of the men and women "survived." All were stunned by this surprise exercise, rudely awakened to their lack of fitness and their potential for mental panic and paralysis. After a 6–week mind–body fitness and resilience boot camp, the group repeated the challenge, and everyone succeeded. They had transformed into fit survivors.

Struck by the daily onslaught of news stories depicting extreme survival challenges—9/11, epic tsunamis, wild fires and hurricanes—I've come to realize that classic functional fitness training needs a survival twist. And that's for everything from falls at home alone to running for your life.

Fitness professionals frustrated by clients who don't seem to grasp the importance of physical activity might consider adding a deeper survival meaning to their workouts. When lives are at stake, fitness has a purpose anybody can grasp. Ten biceps curls take on new meaning if you're envisioning the need to lift a loved one to safety. After falling, a pushup maneuver and aerobic fitness enable people to get up quickly and keep running from the truck that's barreling down on them.

Of course, the TV series locked in on the drama and trauma of life–threatening survival challenges. But survival of the fittest in the 21st century means much more. It's about having an integrated approach to being fit enough to live one's life to the fullest—surviving the daily grind and preparing for life's unexpected curve balls.

Accomplishing this fit-to-live mission requires weaving together five critical elements: mental, nutritional, physical, financial and environmental fitness.

1. Mentally Fit to Live

Life is largely a process of adaptation to the circumstances in which we exist. The secret of health and happiness lies in the successful adjustment to the ever–changing conditions on this globe; the penalties for failure in this great process are disease and unhappiness.

—Hans Selye

Bulging biceps and a high IQ are not enough to escape a burning building or, for that matter, cope with a bullying boss. What's needed is mental resilience—the ability to adapt to life's stresses. Imagine an elite athlete constantly monitoring her surroundings, instantly pivoting to alter course when the weather or terrain changes, or if an opponent tries something new.

Resilience derives from the Latin for "springing back" or "jumping back up." To be resilient means effectively adapting to significant adversity (Fleming & Ledogar 2008).

So what does resilience look like?

Consider the Northwestern University SuperAging Project, which uncovered a key characteristic of people over 80 who have maintained strikingly high mental and physical performance (Rogalski et al. 2013). These gold-medal winners of the golden years did not fear the mental or physical discomfort of learning something new. Instead, they doggedly practiced new skills or habits. Throughout their lives they embraced the importance of always working hard at something, pushing their envelope, and accepting the pain and work that this entailed.

Stress is the great nemesis of resilience, studies have found. Walter Cannon, a pioneer of stress physiology, coined the term homeostasis to describe staying within acceptable ranges of biological and psychological markers (Goldstein 2010). This psychobiological balance is constantly threatened by internal and external environmental stimuli or stressors. Hans Selye, another revolutionary stress–science pioneer, first popularized stress as a medical concept. In his seminal text, Stress without Distress (Lippincott Williams & Wilkins 1974), Selye defined stress as "the non–specific response of the body to any demand made upon it," with that response including fight and flight (Selye 1974). The research community came to view stress as a double-edged sword—integral to survival but toxic and life-threatening when excessive.

Optimal mental fitness requires calming the storm of stress. Practicing resilience protects the mind–body from moment-by-moment stress attacks. How? Start with meditation. Science has shown that meditating is one of the most powerful tools for staying centered and focused.

Scientists have demonstrated-matter density and enhanced connectivity between the prefrontal cortex, which coordinates attention and decision making, and the centers of emotion (Holzel et al. 2011; Vestergaard-Poulsen et al. 2009; Froeliger et al. 2012). Studies have also demonstrated that consistent meditation affects gene expression, favoring less body inflammation and augmenting immune function (McEwen 2016).

2. Nutritionally Fit to Live

Tell me what you eat, and I will tell you what you are.

—Jean Anthelme Brillat–Savarin

Food science experts agree that optimal performance requires a diet that is based on whole foods and that avoids (or significantly minimizes) refined and processed foods. The right kinds of food help regulate metabolism and keep off the extra weight that slows people down in a crisis.

Most processed food is manufactured with heavily refined ingredients—sucrose and a laundry list of additives, including preservatives, texturants, colorants and artificial flavors (Stanhope, Schwartz & Havel 2013). Most of these foodlike products are created with combinations of hyperpalatable processed sugar, fat and salt.

Consequently, the brain's reward system can often become overstimulated, much as we see with drug addiction (Kenny 2011). The pathways in this reward system connect the ventral tegmental area (VTA), the nucleus accumbens and the prefrontal cortex, all integral to pleasure and impulse control. Scientists believe this seeming hijacking of the reward center can, in vulnerable brains, lead to addictive eating and consequent weight problems (Volkow et al. 2012; Peeke 2013).

Processed foods also mess with metabolism. One study compared the postprandial energy expenditure—metabolic heat from the body when it breaks down nutrients—of eating a whole–food diet vs. a processed–food diet with the same number of calories. The researchers found that the postmeal energy output of the processed–food diet fell by a shocking 47% compared with the whole–food diet (Barr & Wright 2010). Such depressed metabolism most likely contributes to long–term weight gain.

The bottom line is that a whole food-driven diet is the optimal way to fuel mental and physical survival skills.

3. Physically Fit to Live

The man who goes afoot, prepared to camp anywhere and in any weather, is the most independent fellow on earth.

—Horace Kephart

Functional physical activity training is a welcome trend in the fitness industry. Fitness professionals are moving away from the traditional three sets of 12 repetitions lifting a single weight and are focusing on the specific purpose of an activity. Moving the body through a variety of planes (torquing, flexing and balancing) more realistically mimics real-life activities of daily living—and potentially life-threatening situations.

Much of the functional-movement revolution reflects the desires of aging baby boomers to maintain the strength, endurance, balance and flexibility they need for vibrant and independent lifestyles. Repeatedly, scientists have shown that successful aging and decreased disability coincide with optimal cardiopulmonary endurance, mobility, muscle strength and balance (Lin et al. 2016). Functional fitness matters at every age, however. It affects both body and mind, starting in childhood, when aerobic activity has a profound effect on cognition, brain structure, academic achievement, behavior and psychosocial functioning outcomes (Lees & Hopkins 2013; Chaddock et al. 2011).

Taking It Outside

Where should we apply functional fitness? These days, growing numbers of fitness professionals worry that contemporary workouts are too domesticated and lack real-world challenges. Their thinking: To go inward and tap into a client's power of survival, try to go out.

As in Outward Bound, whose motto is Sometimes, you need to step outside, get some fresh air, and remind yourself of who you are and who you want to be. Or as in Wild Woodsman Workout, where you step into the wilderness to discover your inner logger, and required equipment includes ax, backpack, bucksaw, water, insect repellant and boots. (After finding a downed tree, you cut to the core for a real–world abdominal workout.)

Flipping to a military nuance, Eat, Move & Defend—a tactical survival training group—offers "Prevent Thrive Survive," a unique training series that combines self-defense with functional fitness and nutrition. Or if you'd prefer to cavort with the living dead, there's "Are You Fit Enough to Survive a Zombie Apocalypse?," a blog post by Jerred Moon on the website for his business, End of Three Fitness. Could you run, jump and climb your way to safety? How about negotiating a tall metal fence with sharp points or barbed wire with a pack of snarling pit bulls bearing down on you? Your exercise prescription would include pull-ups, pushups, dips and box jumps. Remember the stairs in the burning building? Running, squats, lunges, sprints and broad jumps will get you to the top.

A more sporting option is Tough Mudder®, a 10- to 12-mile mud race/obstacle course billed as "An escape from the everyday" where you "won't just face your fears—you'll knock them down . . . test your strength, stamina and grit . . ." and end with a promise of free gear and beer. Moving from mud to TV, the depiction of fitness has morphed from Biggest Loser fat-loss competitions with their endless, merciless treadmill drills to all-out jaw-dropping warrior challenges like American Ninja Warrior and the popular voted-off-the-island Survivor series.

For a good historical summary of the evolution of physical fitness from the time of the functionally fit Greeks to today's in-and-out-of-the-box CrossFit® die-hards, check out the book Lift: Fitness Culture, From Naked Greeks and Acrobats to Jazzercize and Ninja Warriors by Daniel Kunitz (Harper Wave 2016). Those loin-clothed Greco Roman warriors weren't wasting time counting off concentration curls in some arena. They were out in the fields tossing enormous rocks in preparation for war.

Given the science and growing consumer interest in functional fitness, perhaps it's time to create more engaging survival-based training for those who strive to be fit to survive.

4. Financially Fit to Live

The first wealth is health.

—Ralph Waldo Emerson

Fitness pros need to think about—and talk about—the connections between health and wealth. After all, people must be financially fit in order to enjoy the survival benefits of optimal nutrition, physical activity and stress management.

The health and wealth interplay has attracted in-depth research in the public and private sectors. The more money people have, the lower their risk of disease and premature death (NCHS 2012; Braveman et al. 2010). By age 25, the highest earners can expect to live more than 6 years longer than their poorer counterparts (Braveman, Egerter & Barclay 2011; Woolf et al. 2015). Studies show that income (earnings and other money acquired each year) correlates with better health, and wealth (total net worth and assets) also affects health (Pollack et al. 2013).

By contrast, people with limited financial resources are more than three times as likely to have physical activity limitations and disability due to chronic illness (Braveman & Egerter 2008). They also have higher rates of heart disease, diabetes, stroke and other chronic disorders than wealthier Americans (Schiller, Lucas & Peregoy 2012). Risk factors escalate, with prevalence of smoking in poorer households three times the rate of wealthier groups (Schiller, Lucas & Peregoy 2012). In the poorest sectors, obesity rates are also higher (Schiller, Lucas & Peregoy 2012), and the proportion of adults meeting basic physical activity recommendations is just 36%, compared with 60% for those with higher incomes (NCHS 2012).

Clearly, access to affordable health care and insurance is greatly restricted in poorer populations, with 23% noting no usual place of medical care, compared with 6% in the wealthier groups (Schiller, Lucas & Peregoy 2012). The more affluent enjoy the benefits of a safe living and working environment that supports a healthy overall lifestyle. This year, let's usher in a new era of democratizing health for everyone. It's no longer about keeping the 1% fit. Fitness professionals need to help all people become healthy as well as "wellthy," and finally level the health and wellth playing field.

We also cannot ignore the link between financial resources and mental health. Families with incomes of $35,000 or less, compared with those that earn more than $100,000 per year, report feeling anxious and nervous, and are five times more likely to say they are sad most of the time (Schiller, Lucas & Peregoy 2012). These signs of poor mental health parallel complaints of physical symptoms related to stress and depression (Woolf et al. 2015).

What can personal trainers do to address these inequities, especially if their clients are primarily affluent people? Start by thinking about how you can help low-income people prioritize their health and gain access to products and services that could improve their health and well-being. It could be apps, wearable technology, sneakers, athletic clothes, workout equipment, a gym membership, a nutrition expert, a trainer or a meditation retreat. Additionally, find ways to volunteer in financially challenged communities and be of service to people who desperately need guidance in how to prioritize health in their daily lives.

5. Environmentally Fit to Live

The adaptation of individuals to the needs of the body, the community and the environment in which they live is mandatory for survival.

—Erik Erikson

The fifth fitness survival element requires creating and nurturing a unique ecosystem in the environment where you live, work and play. That means managing relationships with the people, places and things in your home, work and outdoor living spaces. Without daily vigilance and upkeep, chaotic clutter can push self-care to the wayside.

It's difficult to pound the pavement if you don't have sneakers. If the kitchen looks like a bomb went off in it and healthy fare is nowhere to be found, you're not going to eat nutritious meals.

Studies back this up: A chaotic kitchen can lead to increased calorie consumption, and messes can cause stress that elevates cortisol levels and increases anxiety and depression (Vartanian, Kernan & Wansink 2017). UCLA researchers at the Center on Everyday Lives of Families examined the relationship between clutter and living environment. Their study results are summarized in the text Life at Home in the Twenty–First Century: 32 Families Open Their Doors (Cotsen Institute of Archaeology Press 2012).

Here's some of what they found:

  • Managing the volume of possessions was such a crushing problem in many homes that it elevated levels of cortisol for mothers.
  • Fragmented dinners—where family members eat sequentially or in different rooms—have redefined the traditional family dinner ritual.
  • Even in a region with clement year-round weather, families hardly used their yards, even those who had invested in outdoor improvements and furnishings (Arnold et al. 2012).

This third finding segues into the powerful health benefits of being outdoors in natural surroundings. Ecopsychologists have touted the profound improvements in mood, depression and stress hormone levels that occur when people go out in nature (Hartig et al. 2011; Howell et al. 2011). Daily nature walks predict greater functional fitness, more life satisfaction, elevated mood and increased longevity in older adults (Jacobs et al. 2008).

Hug a tree. Plant something in the ground. Take a hike. It's all good for survival of the fittest.