Researchers at the University College London in Britain looked at 3,722 couples, either married or living together and over the age of 50, who were taking part in the English Longitudinal Study of Aging.

They found that people were more successful in swapping bad habits for good ones if their partner made a change as well.

For example, among women who smoked, 50 percent managed to quit if their partner gave up smoking too at the same time, compared with 17 percent of women whose partners were already non-smokers, and eight percent of those whose partners were regular smokers.

The study found that men were equally affected by their partners and were more likely to quit smoking, get active, or lose weight if their partner made the same behavior change.

"Now is the time to make New Year's resolutions to quit smoking, take exercise, or lose weight," lead author Sarah Jackson of the University College London said in a statement.

"And doing it with your partner increases your chances of success."

The study was published in the U.S. journal JAMA Internal Medicine.