If exercise is healthy (so good for you!), why do many people dislike or avoid it? If we are born to walk and run, why do most of us take it easy whenever possible? And how do we make sense of the conflicting, anxiety-inducing information about rest, physical activity, and exercise with which we are bombarded? Is sitting really the new smoking? Can you lose weight by walking?   Does running ruin your knees? Should we do weights, cardio, or high-intensity training?  In this m