In the study, they followed about 1,000 people for a year to see if they followed their New Year's resolutions.
At the end of the year, 55 percent of the participants managed to keep their promise.
Approaching and avoiding
It went very well for those who had started with something new, which is called the approaching goal.
It went worse for those who wanted to quit or avoid something, which is called avoidant goals.
- If you want to stop eating sweets, maybe you can instead have the New Year's promise that you will start eating two fruits a day, says Per Carlbring.
Hear more about how you can succeed with your New Year's promise in the clip above.