No sweat How the simple science of motivation can bring you a lifetime of fitness.

We always start with the best of intentions when we begin a new exercise program. In fact, we could not be more determined to tone our bodies and get in shape! But then our planned week of five days at the gym or doing an at-home program turns into three days, into one day, into . . . Who has the time?The truth is, we still really do want to be healthy and fit, but we have become so overwhelmed and overextended with other nonnegotiables in life t...