We asked experts on behavior change how they recommend approaching three of the most common New Year's resolutions. The advice can be generalized to just about any goal, so read on even if you have a more unusual challenge ahead of you.

Resolution #1: Eat healthier

“New Year's resolutions are often too general,” says Phillippa Lally, a research psychologist at University College London. She emphasizes identifying specific behaviors, deciding when to perform them and then doing so repeatedly. For instance, map out when you will eat your five servings of fruits and vegetables—one with each meal, one for your midday snack and one after dinner. At some point you will likely give into temptation, she says, but do not be deterred. Forming a new habit can take anywhere from 18 to 254 days, according to one study by Lally and her colleagues.

Resolution #2: Quit smoking

“We can improve self-control through practice,” says Mark Muraven, associate professor of psychology at the University at Albany. In fact, Muraven notes, increasing our willpower is similar to strengthening a muscle. In a recent study, he found that smokers remained abstinent longer if they exerted self-control in other areas, such as cutting back on desserts, before attempting to quit. Don't overdo it, though—willpower can get depleted if you try to exercise it too much. Focus on your primary goal. If you keep slipping up, cut back on other attempts to use self-control.

Resolution #3: Spend less, save more

“If you're uptight and stressed while trying to modify a behavior, you actually inhibit yourself from changing, but if you're playful and flexible, you may become more open to figuring out a way to reach your goal,” says B. J. Fogg, an expert on behavior change at Stanford University. Changing your behavior should not feel like drudgery. To save money, for example, be creative about how to cut back. Find a quirky vintage shop to purchase your winter coat or experiment with new recipes that make cooking more enticing than eating out.