06/21/2010 05:12 am ET Updated May 25, 2011

Harvard Study: Good Deeds Improve Willpower

People gain more willpower to do good after performing a good deed, according to a recent Harvard study.

Psychology graduate student Kurt J. Gray found that people who chose to donate a dollar rather than keep it had greater physical endurance.

"To be good and feel the positive effects, you just have to do some good," he said. "You don't have to donate a whole kidney. You can just donate a dollar."

Read more on The Harvard Crimson