You don’t have to run a marathon to be fit and healthy, or suffer through a triathlon that includes a half-mile swim in the ocean. But you do need an exercise habit. Especially as we age, exercise is not optional. Yet unless we had been athletes as kids or young adults, and few of us were, we do not know how to find our edge. Learning how to carve out time to meet our fitness needs or to push ourselves physically and mentally is one of the greatest challenges to aging well.Inspired...