You see chocolate cake, you want chocolate cake…but you also want to stick to your diet. What do you say to yourself? As you struggle against temptation, your “self-talk” matters—because the specific words you use to frame your refusal have a big influence on how you feel…and on whether you surrender to or successfully subdue the craving.

Researchers looked at the effects of two different “refusal strategies” for dealing with temptation, using either the phrase “I don’t” or “I can’t,” in four separate studies involving a total of 449 participants. For instance, participants were coached to say to themselves, “I don’t eat chocolate cake” versus “I can’t eat chocolate cake”…or “I don’t skip my workout” versus “I can’t skip my workout.”

Findings: Participants who said “I don’t” rather than “I can’t” when faced with temptation reported feeling more empowered and in control. They also made healthier food selections—for example, when offered a choice of a candy bar or a granola bar, 64% of the “I don’t” group but only 39% of the “I can’t” group opted for the more healthful granola bar.

Additionally, one of the studies demonstrated that the “I don’t” strategy led to longer-term positive behavioral changes. Participants were asked to try their assigned refusal strategy for 10 days, though they were allowed to give up if it wasn’t working. In the “I can’t” group, 90% gave up within four days—but in the “I don’t” group, 80% were still using the strategy after the full 10 days. Participants also reported that saying “I don’t” helped them to bike instead of drive…take the stairs instead of the elevator…choose smaller portions…and even arrive at work on time instead of with their habitual tardiness!

Explanation: Though the two phrases often are used interchangeably in everyday language, “I can’t” conveys a lack of control and a sense of deprivation that hinders motivation…whereas “I don’t” is an empowering and self-affirming message that motivates a person to keep on striving. Exception: When there is an external motivating factor, such as an upcoming important event, “I can’t” is the more effective refusal strategy, researchers noted. So if the goal is to lose weight in time for a friend’s wedding, saying “I can’t eat fast food until the wedding” can inspire a greater sense of accountability and commitment to the short-term cause. For long-term success, however, stick with “I don’t.”