Adding weights to your workout routine might help you live longer than just doing aerobic exercise alone. In a new study published in The British Journal of Sports Medicine, researchers collected data on over 400,000 adults who completed questionnaires about their exercise routines, including how much and what types of exercise. They found that adults who performed one hour of moderate to vigorous aerobic activity a week had a 15 percent lower mortality risk. For those who got three hours of exercise each week, their risk of mortality dropped 27 percent. But for those who also did one to two strength-training sessions per week, they had a 40 percent lower risk of death. The researchers say that is essentially the same difference between smoking a half-pack of cigarettes a day and not smoking at all.