It is the end of the year—a time when millions of people make promises to improve their lives and themselves. According to a recent Marist Poll, 59 % of people kept their New Year resolutions in 2014. So what is it that makes a resolution stick? One expert, Judith Beck, Ph.D. , president of the Beck Institute for Cognitive Behavior Therapy in Philadelphia and a clinical associate professor of psychology at the University of Pennsylvania, explains the benefits of a buddy system and why vague goals fail.

For All Those Procrastinators
New Year’s resolutions tend to encompass big commitments that people have put off. “Usually these are things that are difficult to do, otherwise we would have done them already,” explains Dr. Beck.

The most common January goals focus on weight loss and better general health, but nearly all of them fit into one of seven categories: physical health, organization, relationships, how to spend leisure time, spirituality, creativity and work. “Some people want to get back to the way they used to be, and are committed to making a full-fledged effort,” Dr. Beck says of the goal-setters. “Others want to expand themselves and feel more fulfilled in life.”

The Stickiness Problem
As any visit to a gym in January will attest, most people can persist with a resolution for a few weeks. But by February, that drive is often depleted and the treadmills go empty. “There is some research to show that people who start trying to lose weight because they’ve had a medical scare are more successful than people who do it for another reason,” explains Dr. Beck. In other words, “Often the resolution will stick if the stakes are very high.”

Happy New Year  Typically, though, people fail to stick to their annual goals because the resolutions are too demanding, vague or unrealistic. “There can also be external factors. If your objective is to spend more time with family, you may need the cooperation of your teenagers to plan more outings, for example,” Dr. Beck says.

Learning to Cope
When people feel unmotivated or discouraged, says Dr. Beck, they have unhelpful thoughts that interfere with working toward their goal. “So you need to predict in advance what thoughts you might have, when you’re feeling more gung-ho—like now, before you’ve even started—and write them down,” says the cognitive-behavioral therapist. “Nobody is taught how to get back on track when they make a mistake,” she says, but a person can take control of sabotaging thoughts by reading those responses daily.

Dr. Beck also advises clients to imagine themselves in a year or five years, both having reached their goals and establishing them as habits and having failed.

“No-Choice” Category
Most people have some positive behaviors that they might not consistently want to do but they decide to always do anyway. Dr. Beck calls this the “no-choice category,” and places putting on a seat belt or getting dressed for work in this column. “We do them without struggle because we don’t give ourselves a choice,” she says. “It’s the choice that makes sticking to a resolution so difficult.” She suggests putting positive behaviors on a mental “no-choice” list and reaffirm them daily. “If you never give yourself the option to eat dessert, you’ll never have the struggle,” she says.

Don’t Wait to Motivate
Dr. Beck has witnessed firsthand that taking action sparks motivation. “Once you actually get to the gym, the first minute may be difficult, but it almost always gets easier,” she says. She also says that the best way to stick to a resolution is to have an accountability system, whether that is an app or a partner, she says.

When you do put on those gym clothes, she adds, you need to congratulate yourself. “Constant affirmation is essential to success,” says Dr. Beck.