The New York Times on willpower:

One of their newest studies, published last month in the Journal of Personality and Social Psychology, tracked people’s reactions to temptations throughout the day. The study, led by Wilhelm Hofmann of the University of Chicago, showed that the people with the best self-control, paradoxically, are the ones who use their willpower less often. Instead of fending off one urge after another, these people set up their lives to minimize temptations. They play offense, not defense, using their willpower in advance so that they avoid crises, conserve their energy and outsource as much self-control as they can.