Sleep to stay strong. If you've ever adopted a to-heck-with-it mentality when you're exhausted, here's why: "Research shows that when we're sleep-deprived or have low blood sugar, our willpower goes way down," Martela says. Try to snooze for at least seven hours a night and have a healthy nibble every few hours during the day.
Bet on yourself. To stay on track, put something you value on the line. People who promised to forfeit money if they failed to lose weight shed 14 pounds more than those who didn't have anything at stake, according to a study in the Journal of the American Medical Association. Sign up for stickk.com; if you don't succeed, the amount you bet will go to a friend or your favorite—or least favorite—charity. Talk about major motivation!
Look on the bright side. Instead of thinking about what you're giving up, reframe your mind-set so that you focus on the benefits—for instance, getting to the gym before work will free up the night to have fun with friends, or packing lunch will help you save money to afford a tropical vacation. "Focusing on what you can gain from your efforts energizes you to keep going," Martela says.