I practice what I preach. My workouts are scheduled and there are very few things that can take presidence over my schedule. I prioritize as much as possible. I would say that less than one time out of 100 does something come up that disrupts my schedule. Part of it is good planning. Part is being ready to say no. And part is considering my health and fitness to be the most important part of my schedule. I am much more efficient mentally and physically when I am getting my workouts accomplished.
As for having the energy, that is part of why my workouts are a priority. Without my workouts, energy would be a problem all of the time. Sure every now and then I get really tired. But I assess whether I have the energy to properly workout and workout accordingly. But those times are very rare.