Self-control is critical to productivity at work. It keeps you from zoning out, losing your cool, and giving up easily.

However, a large body of research suggests that exercising self-control in a broad range of situations, including resisting chocolate and choosing which household products to buy, can make you a less motivated and responsible decision maker. This phenomenon is known as ego depletion. So how can that self-control be restored?

One promising avenue is self-affirmation, which has been proven to make people less defensive. Because defensiveness is an impulse, researchers are now studying whether self-affirmation affects other impulses as well. In one recent study, subjects did a self-control exercise that involved writing a story without using the letters a and n. Some of the subjects were then asked to write about a value that was important to them. The other subjects were instructed to write about why one value might be important to the average student.

Finally, all the participants took a pain tolerance test, holding their hands in freezing water. Subjects who had just affirmed their basic values lasted about 30 seconds longer on average than members of the no-affirmation group, according to Texas A&M's Brandon Schmeichel, a co-author of this study.

Thinking about values encourages abstract thinking, which has long been considered a key factor in self-control. This research has implications for the workplace. "Self-control is about competition between immediate and delayed gratification," Schmeichel says. "If you're tempted to take a shortcut instead of a principled decision, reminding yourself of your mission statement or anything that reorients you to the long term should help you make the right choice."