Let’s get down to physics. Strength is the ability to overcome a resistance. Work is the ability to overcome a resistance, a 100 # barbell lifted thru 2 feet 10 times (2,000 ft/lbs) of work. Power adds in time. Doing the lift in 4 seconds is more powerful than doing it in 10 seconds.
I think that strength is a major component of overall fitness. There are any number of ways to work against resistance, as has been suggested. Just do it. If it’s your body weight or a barbell, make your muscles work.