I think habit-management is a pretty critical skill if you want to get anywhere in life.
Your genetic and cultural heritage decides where you start out in life, and external circumstances may throw you a few curve balls even when you’re older, but the older you get, the more your position in life is a direct function of all the small choices you’ve made, whether you’ve been aware of them or not (as the case often is with habits).
This certainly includes exercise, but also choices like whether to picking up a book rather than vegetating in front of the TV, or keeping in touch with old friends.
Our nature is significantly less immutable than we often think it is. Habits are devious little bastards that make us think we’re not making decisions when we really are, the same decisions, day after day. But it goes both ways — if you leverage this, then going to the gym three times a week becomes as obvious as putting on pants in the morning or brushing your teeth.