Why New Year’s resolutions are so hard to keep

Moshe Bar, director of the Cognitive Neuroscience Laboratory at Mass. General and Harvard Medical School, explains that there’s more to the issue than willpower.


I quit smoking on a Monday last August, outside JFK airport. I gave my pack to an appreciative stranger, who smiled with sympathy and said that the last time he quit was outside Chicago’s O’Hare. I had been smoking three cigarettes a day for many years; never been tempted to quit in earnest, but also rarely felt an urge to smoke more. But 42 days after quitting, I bought another pack and lit up. You know the story.

Chances are, a couple of weeks ago you made a New Year’s resolution that involved your health – maybe you wanted to quit smoking, drink less, or shed a few pounds. And chances are, your resolve is already wavering. There hasn’t been much research on how well people stick to their resolutions, but it looks as if many fold within a mere two to six weeks. In other words, right about now.

Why is it so difficult to stop doing things we know are bad for us? The answer lies in recognizing a couple of intriguing ideas about how our brains work. First, they seek to be rewarded constantly. Second, those rewards – manifested as pleasure and positive mood – are made up of neurotransmitters such as serotonin, dopamine, and endorphins. These molecules stock the shelves of the best opium den in the world, the one right between our ears, and we’re all hooked on them.


Each of us has an optimal mood “zone,” the mood in which we prefer to be, and trying to get there guides many of our choices. One way to reach the zone is by being an active and productive member of society. Achieving at work, watching your child score a winning goal, buying a house, publishing a much-talked-about paper, getting even the smallest recognition, all result in a reward of brain chemicals. Neurotransmitters are nature’s trick for encouraging us to do what is supposedly best for us.

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But there are also shortcuts to getting the same rewards without the effort that they normally require. In a famous experiment from the 1950s, scientists implanted electrodes in the brains of rats in areas that were later dubbed “pleasure centers.” The rats controlled the flow of current by pressing a lever.  The pleasure they elicited by doing so was so effective that they pressed the levers almost nonstop – sometimes 2,000 times an hour – forgoing even food and water until they collapsed from exhaustion.

For humans, using drugs or alcohol can be like pressing that lever: shortcuts to feeling good. After all, why spend an hour sweating on a treadmill if a few martinis can give you the same buzz?  Sure, we can exercise more inhibition and self-control than rats, but not all of us to the same extent. If reaching our optimal mood zone isn’t easy – if we need more to get there because of our genes or environmental factors such as stress or exposure – we compensate with less constructive behaviors.

But this does not mean that we need to accept our inherent addiction to neurotransmitters. Granted, just as an Alzheimer’s patient cannot choose to start remembering better, heroin addicts (and two-pack-a-day smokers) cannot simply wake up one morning and quit. But people with less intense dependencies can choose different ways to fill up their “buckets” of mood molecules. Hard work, chocolate, sex, exercise, and even TV and e-mail can all help us get to our desired zones. Interestingly, choosing one way of filling up the bucket may reduce the need for another, which may explain why antidepressants tend to reduce libido and why runners consume fewer candies.

Keeping the mood bucket in mind (which is where it is anyway) can guide us toward better choices and more sustainable resolutions. If we can get the same reward neurotransmitters from a variety of everyday activities, a promising strategy for kicking bad habits is to replace them with good ones that yield similar levels of reward. Rather than indulge in an extra helping of dessert, you can put in some time cleaning up the attic. Rather than heading to the bar after work, you can take up cycling or tutoring. Those alternative sources of reward are not only healthier, but their buzz lasts longer.


No matter how much we try to drop bad habits, however, our brains still need variety. The rewarding aspects of sipping scotch by the fire on a snowy evening go beyond a specific neurotransmitter. So even as I hope to someday swap cigarettes for half marathons, I’ve accepted that I’m stuck with my Skittles addiction.

Moshe Bar is the director of the Cognitive Neuroscience Laboratory at Harvard Medical School and Massachusetts General Hospital. Send comments to