Have you already abandoned your New Year’s resolution? No need to feel ashamed. Fully a quarter of the people who make resolutions give up by the end of the first week, with many others falling off the wagon in the months to come. It seems to be human nature to aim high and fall short.

Whether attempting to exercise more regularly, cut back on impulse buying or simply keep a tidy desk, anybody who has tried changing a long-standing habit knows how frustratingly hard lasting change can be. But why is it so difficult, despite our good intentions? What do those few who succeed know that the rest of us do not?

These questions are as intriguing to scientists as they are to those of us aiming toward our own goals, and decades of research have given us a good idea of the answers. Lifestyle changes require adjustments to mind-set, motivation and intent. Dreaming big is fun, but setting realistic expectations will prepare you better for the challenges to come, as will putting specific plans in place for when you face them. Start small with short-term, achievable goals to build up your confidence as you move forward. Find a deep, personal motivation that can keep you feeling accomplished and in control of your fate. Create new routines that will make your desired behaviors as automatic as the bad habits you wish to break.

The best news is that by using these techniques, even drastic personal revolutions are eminently achievable, without the help of doctors or programs. “Most of the time people do make positive changes on their own, which is important for everybody to remember,” says Richard M. Ryan, a psychologist at the University of Rochester. Here’s how you can do it, too.

Old Problems, New Approaches
Scientists have long been tackling the problem of how to get people to do what is good for them. Until the past 10 to 15 years, however, most ideas have not stood up to real-world testing, says Martin Hagger, a health psychologist at Curtin University in Perth, Australia. For instance, scholars thought that individuals would not smoke if they understood that doing so is bad for them. Yet no amount of information about smoking’s deadly effects proved to have much of an impact on quitting rates. It turns out that we have a much harder time changing our actions to align with our thoughts than the other way around. It is far easier, in other words, to make excuses for why we are still smoking—or eating junk food or not flossing our teeth.

Today’s researchers are looking beyond older notions of willpower, finding that successful reform requires much more than the ability to control your impulses. A crucial first step is to know going in that mending your ways will not be easy. Understanding why will help smooth the bumps on the road ahead. “What makes habits hard to change is what makes them so useful,” says Wendy Wood, a psychologist at the University of Southern California who studies habit breaking. Habits make life easy, so we do not have to think about things such as putting on our shoes before leaving the house. Simply being in a particular place prompts the action—a fact that, unfortunately, is equally true for those peccadilloes we wish to eliminate.

A stark demonstration of this reality is a recent experiment by Wood and her colleagues, published last year in the Personality and Social Psychology Bulletin, in which they gave either fresh or week-old popcorn to subjects who habitually ate popcorn at the movies. They ran the test in several environments. Nobody particularly liked the stale popcorn, but they nonetheless ate just as much of it as the fresh stuff. The good news was that this pattern held only when they were watching movie trailers in a theater but not while watching music videos in a conference room, where the change in cues blunted the mindless impulse to eat. Planning ahead to minimize such situational hints is one way to break habits—if you are trying to give up caffeine, for instance, find a route to work that does not take you past Starbucks.

Forming a new habit, so as to get in shape or read more classics, for example, usually requires choosing between the pleasant or familiar and something much less so. Most people overestimate the ease of this willpower challenge, which gets them into trouble. In a set of experiments published in Psychological Science in 2009, participants with the highest opinions of their self-restraint were the most likely to give in to temptation, whether it was in the form of cigarettes or fatty snacks. Those with the most modest, realistic assessment of their abilities, on the other hand, fared best.

Lasting change, of course, requires making the right choice time and time again for the rest of your life—in all kinds of difficult situations. “If you simply think, ‘I can do it. I simply have to refrain,’ then you’re likely to fail because things are harder than that,” says Mary Jung, a University of British Columbia researcher who studies health behavior. Remember that lapses are normal rather than a sign that you should give up. “If you missed a day of exercise, that doesn’t mean you’ve failed,” Jung says. “It just means that tomorrow you’ve got to get your workout in.”

Research suggests you should spend some time imagining both the successful result of your efforts and the specific obstacles that will stand in your way. Instead of resolving abstractly to save more money this year, for example, you might form two mental images: one might be of a larger bank balance, and the other of yourself wrestling with the decision to not join your friends at a pricey new restaurant. Studies find that after engaging in this two-step technique, called mental contrasting, people procrastinate less and tackle challenges more enthusiastically.

Find Your Own “Why”
To maximize your chances of sticking to a goal, you need to figure out exactly why you are pursuing that objective in the first place. “The ‘shoulds’ might get you going for a month or two, but they’re not easily sustained,” says Ryan, who, with his colleague Edward L. Deci, developed a model of motivation called self-determination theory. It posits that individuals feel most fulfilled when they are meeting their essential psychological needs: a sense of competence, relatedness to other people and, most important, autonomy, or the sense of freely choosing what you do.

To meet the need for competence, look for activities that help you feel the inherent satisfaction of being good at something. Tracking your progress—by logging your practice times, for instance—is one way to bolster that sense of accomplishment.

We all strive to feel close to others, which is one reason why buddying up increases your probability of sticking with a goal. To perceive your resolution as satisfying this psychological need, think about the ways your new habit will improve your relationship with your loved ones, connect you to new people or bring you closer to your community.

The thirst for autonomy, the final pillar of self-determination theory, is so strong, Ryan suggests, that if you are motivated only by external pressure, sooner or later you are bound to rebel and sabotage your own efforts. Finding activities that meet your personal needs, on the other hand, will improve the odds that you will stay on target.

We ignore the importance of these internal motivators at our peril, as shown by research on the effect of financial incentives for losing weight. Short-term studies as early as the 1970s offered promising results, with cash rewards inducing people to shed more pounds than without the incentive. “Now we have long-term studies that show that the moment you take off the pay, people start relapsing,” says Pedro J. Teixeira, a professor at the Technical University of Lisbon in Portugal who co-authored a paper describing a much more successful weight-loss intervention, published last year in Medicine and Science in Sports and Exercise. In the study, overweight women who had been encouraged to explore their personal motivations and to choose their own goals exercised far more, and lost significantly more weight, by the three-year mark than women who did not tap into their autonomy.

If your goal originated from an external source, you can still make it your own—and increase your chances of achieving it—by finding your personal reasons to pursue it. If a doctor tells you to watch your cholesterol, for example, you can ask yourself how your food choices help or hinder your pursuit of your larger aspirations, such as spending time with your grandchildren or traveling more. This process can help you see the external goal as a path to becoming the person you want to be, enabling you to embrace it more fully.

Teixeira sees deep-rooted, autonomous drive as the key that unlocks all the other doors to lasting change. “When adequately motivated, a person will ultimately find the single best solution for his or her problem,” he says.

Take It Slow and Steady
Another key to making lasting changes is to start modestly and work up to bigger challenges gradually—the way successful running regimens urge couch potatoes to start by walking and to pick up the pace little by little over a few weeks. “It is so defeating to put effort into something and then fail,” says Jung, who has worked as a personal trainer and fitness instructor. Part of her credo is: “If I don’t know whether they can do it, it’s not a good task for them to start with.” Yet as sensible as that sounds, most people take the opposite approach—most commonly through extreme diets but also with sudden vows to practice the piano for an hour a day or to read the complete works of Charles Dickens instead of watching the latest season of Jersey Shore.

The gradual approach works because it boosts an essential ingredient in goal achievement: the confidence that you have what it takes to succeed despite real-world difficulties. That kind of faith is quite different from the unfounded optimism of those who overestimate their ability to resist temptation, Jung explains. Being able to overcome external challenges has less to do with willpower than with specific coping skills, such as managing scheduling problems and bouncing back after setbacks. Gradually developing these abilities—by setting modest goals that allow you to encounter manageable problems—boosts your confidence, making you more likely to persist toward your long-term ambitions.

Of course, that belief is shaken every time we stumble. People who have failed repeatedly at sticking to their goals tend to doubt their ability to accomplish anything. “To gain that confidence, you need baby steps,” Jung says. For instance, if you strive to keep your home free of clutter, focus on one room—or even a countertop—at the beginning. Keep that area clean for a week, congratulate yourself, then add another area for the next week. Maintaining one pristine countertop may sound laughably easy—but that is exactly the point. By going after your target one small step at a time, you will reduce the effort it takes to ingrain new habits and improve your self-confidence naturally.

Engage Your Autopilot
Lasting change ultimately requires making the new behavior automatic. One way to start the habit-forming process is to spell out for yourself when, where and how you plan to reach your goals. For example, if you aspire to eat three servings of vegetables every day, you might tell yourself, “When I go home, I will stop by the grocery store and buy vegetables,” says New York University psychologist Peter Gollwitzer, who originated this if-then technique, called an implementation intention. The point is to create an automatic cue to prompt the behavior you want.

In a study published in 2010 in Health Psychology, Gollwitzer and a pair of his colleagues told a group of German women about the health benefits of eating five servings of fruit and vegetables a day. They also instructed some of the women on how to use implementation intentions and mental contrasting. These participants sustained their healthier diet for the full two years that the study ran, whereas the others reverted to their previous produce intake after a few months. Other studies showed that implementation intentions reduced teen pregnancy by 43 percent as compared with a control group in a British city with above-average rates of teen pregnancy, and English preteens likewise smoked less over two years by spelling out what they would say and do when offered a cigarette.

Some types of implementation intentions work better than others. For example, Gollwitzer recently found that tacking on a reason for your plan—as in, “When I get to the cafeteria, I will grab a salad because I want to be healthy”—backfires because thinking about the reason disrupts the automaticity, a result suggesting that you need to be clear on your reasons before you begin your program. Another finding is that the most effective implementation intentions are in positive form—“I will ignore the phone” instead of “I will not answer the phone.” Adding mental imagery also helps; that way “the statement isn’t just written down or repeated like a mantra but actually enacted in your mind’s eye,” Gollwitzer says.

Reach Your Holy Grail
Some of these strategies, particularly the emphasis on realistic goals, looking within and making concrete plans, are similar to those used in cognitive-behavior therapy to treat maladies as serious as anxiety and depression—which should give hope to those of us with more modest challenges. Yet Ryan emphasizes that the vast majority of people do not need therapy to change; after all, most individuals who quit smoking do so on their own.

Keep in mind that some of these tools may not be right for everyone. For instance, past research has shown that implementation intentions do not work as well for deeply ingrained habits. People who want to upend a lifelong routine may not find this technique very useful, just as others might find that their aspiration does not break down easily into smaller steps or present any opportunity for bonding. The important thing is to try a number of tactics and find what works best for you.

Lasting change is hard, but recognizing this difficulty will actually help you be more successful. It takes great effort and specific plans to form new habits, and you must not see your first lapse as a sign of failure. The goals you set should truly be your own, not based on somebody else’s values. Perhaps most important, do not expect to change your ways overnight—even if the night in question is New Year’s Eve. It’s never the wrong time to start taking steps toward a better you.

This article was published in print as "The Secrets of Self-Improvement."