There's nothing easier than falling out of shape, especially in the U.S. Americans may no longer lead the world in science, engineering and productivity, but with TiVo on the flat-screen, Domino's at the door and an arsenal of remotes within easy reach, we've got leisure time nailed.
Climbing off the couch and getting back into condition is a dicier proposition. Trying to do it too fast can actually be dangerous. "Among those at greatest risk for heart-attack death is the habitually sedentary person who engages in unaccustomed physical activity," warns Barry Franklin, physiologist and chairman of the American Heart Association's Physical...