How to Increase Your Willpower

10. Willpower decreases when your spouse or housemates tempt you.

When your husband frequently picks up pizza on the way home and takes you to restaurants and places with limited healthy food options, your willpower may spin out of control. "Being with others who give in to temptation makes it easier to do the same," says Bartell. Even if they're not trying to sabotage your eating-well efforts, bringing high-fat, high-calorie foods into your home can weaken your willpower. Instead of giving in, encourage your spouse or roommates to purchase treats that they like but you don't—potato chips instead of your beloved nacho cheese–flavored tortilla chips, for example. And have healthy snacks at the ready, just in case they're eating your favorite junk foods in front of you.

11. Willpower increases when the weather is warm and the light is bright.

There's a lot to love about warmer months—more sun, higher temperatures—and now you can add this to the list: You crave lighter foods. "With warmer weather, shedding winter clothes and having more hours of daylight, you're more likely to get out of the house and get moving," says Palinski. And healthy eats can help you get there. Cold, wintry weather has the opposite effect: We hunker down, eat warm, fatty foods and limit exercise. And just in case you need an extra shot of willpower come spring, Palinski says to remember: "The thought of putting on a bathing suit just might give you reason to eat well."