Contributor(s): Dr Roy F Baumeister | A new understanding of how people control themselves has emerged from the past decade of research studies. Self-control depends on a limited energy supply, and each person's willpower fluctuates during the day as various events deplete and then replenish it. Decision making and creative initiative also deplete the same willpower supply, while eating and sleeping can restore it. Some circumstances propel people to perform well despite depleted willpower, including power and leadership roles, local incentives, and personal beliefs. People with high self-control specialize less in resisting temptation than avoiding it. Roy F Baumeister is one of the world's most influential psychologists. He received his PhD from Princeton in 1978 and currently is Francis Eppes Eminent Scholar and head of the psychology programme at Florida State University. He was over 450 scientific publications, and Willpower: Rediscovering Our Greatest Strength is his latest book.