(CNN) - Want to double your chances of success in making a positive lifestyle change? Just add a loved one. Researchers at University College London found that couples who adopted a new and positive health behavior were more successful than those doing it on their own. For the study, researchers followed nearly 4,000 married and cohabitating couples, and studied their unhealthy habits in three areas: smoking, obesity and physical activity. They found 48 percent of men were able to stop smoking if their partner also quit. Compare that to just 8 percent who had partners who did not quit. For women, the success rate was half. When it came to physical activity, both men and women had about a 66 percent success rate starting an exercise routine with their partner versus about 24-percent if they started alone. And 36 percent of women lost weight if their partners joined them in a weight loss plan, compared to 15 percent without a supportive partner. The men had a 26 percent success rate with a partner and 10-percent losing weight alone. It's unclear why the relationship matters, but having some support, or a dose of plain ole healthy competition, may just be enough to put you over the edge.