Couples could help each other get healthy and fit if both parties agree to make positive changes together.

Researchers found couples were more likely to quit smoking, exercise more, or lose weight if both partners were working towards the health goal, Cancer Research UK reported.

"Unhealthy lifestyles are a leading cause of death from chronic disease worldwide.  The key lifestyle risks are smoking, excess weight, physical inactivity, poor diet, and alcohol consumption.  Swapping bad habits for good ones can reduce the risk of disease, including cancer," said Professor Jane Wardle, director of Cancer Research UK's Health Behaviour Research Centre at UCL (University College London) and one of the study authors.

To make their findings a team of researchers 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 Ageing (ELSA).

Among women who smoked, 50 percent successfully quit if their partner did the same, compared with only 17 percent of those whose partners were already non-smokers or 8 percent of women whose partners were regular smokers. Similar numbers were seen in men who smoked.

"Making lifestyle changes can make a big difference to our health and cancer risk.  And this study shows that when couples make those changes together they are more likely to succeed," said Julie Sharp, Cancer Research UK's head of health information. "Getting some support can help people take up good habits.  For example if you want to lose weight and have a friend or colleague who's trying to do the same thing you could encourage each other by joining up for a run or a swim at lunchtime or after work. And local support such as stop smoking services are very effective at helping people to quit."

The findings were published in a recent edition of the journal JAMA Internal Medicine.