Willpower

in resisting the effects of depletion (that is, on the last self-control test administered at each lab session). Thus, exercise increased people’s stamina, allowing them to hold out against temptations even when their mental resources had been depleted.
    Not surprisingly, they also advanced toward their goals. Those in the fitness program got fitter; those working on study discipline got more schoolwork done; the people in the money-management program saved more money. But—and here was a truly pleasant surprise—they also got better at other things. The students who did the study-discipline program reported doing physical workouts a bit more often and cutting down on impulsive spending. Those in the fitness and money-management programs said they studied more diligently.
    Exercising self-control in one area seemed to improve all areas of life. They smoked fewer cigarettes and drank less alcohol. They kept their homes cleaner. They washed dishes instead of leaving them stacked in the sink, and did their laundry more often. They procrastinated less. They did their work and chores instead of watching television or hanging out with friends first. They ate less junk food, replacing their bad eating habits with healthier ones. You might think that people who start doing physical workouts would naturally start eating better, but in fact the reverse has often been observed in other studies: Once you start exercising, you feel virtuous and therefore entitled to reward yourself with high-calorie treats. (That’s an example of the “licensing effect,” when you act as if one good deed gives you license to sin.) But in this experiment, the group of exercisers didn’t yield to that temptation. Nor did the group of budget-conscious people yield to the predictable temptation to cut down on their grocery bills by passing up the more expensive fresh foods and other healthy fare in favor of cheaper food. If anything, they began spending more money on healthy food, apparently because of an overall increase in self-control.
    Some of the people even reported improvements in controlling their tempers, an intriguing finding that was tested in a subsequent study of domestic violence by Oaten together with Eli Finkel of Northwestern University and other psychologists. The researchers asked people about their likelihood to become physically aggressive toward their relationship partners, such as slapping or punching them or attacking them with a weapon, in various situations, such as being “disrespected” by the partner or walking in on the partner having sex with someone else. Then the researchers had the participants in the study perform willpower exercises for two weeks, except for a control group. After the two weeks, the ones who did the exercises reported fewer tendencies to behave violently when provoked by a loved one, both in comparison with their own pre-exercise baseline and in comparison with the controls who did not exercise. (For ethical and practical reasons, researchers have to be content with having people report their inclinations to behave violently, as opposed to trying to measure how often people actually hit, assault, or otherwise harm their loved ones.) Improved self-control predicted less domestic violence.
    All in all, these findings point toward the remarkable benefits of exercising willpower. Without realizing it, people gained a wide array of benefits in areas of their lives that had nothing to do with the specific exercises they were performing. And the lab tests provided an explanation: Their willpower gradually got stronger, so it was less readily depleted. Focusing on one specific form of self-control could yield much larger benefits, just as self-experimenters from Ben Franklin to David Blaine had maintained. The experiments showed that you didn’t have to start off with the exceptional self-control of a Franklin or a Blaine to benefit: As long as you were motivated to do some kind of exercise, your overall willpower could improve, at least over the course of the experiment.
    But what about afterward? As remarkable as the results were, the experiments had lasted only a few weeks or months. How hard would it be to keep up the self-discipline indefinitely?
    Here, once again, the case of David Blaine is instructive.

The Toughest Stunt of All
    Before we told David Blaine about the scientific research into willpower, we asked him which of his feats had been the most difficult. This was not a simple