Too many bands practice in their garage, play a couple of shows locally, and expect opportunities to appear from the sky. Bands have to push, work, grind, and struggle to make it happen on their own.
Staying in shape does not come easily, especially as you get older and you don't have as much time or energy to exercise. I used to be naturally skinny in high school and college. I was in cheerleading, ran track, and did gymnastics, so I had a built-in five-hour workout every day. Lately, I've been doing Pilates on the Megaformer, which is like Pilates on steroids.