Marraige can make you live longer

Want to lengthen your life, then get married:

Married men tend to live several years longer than single men. A happy husband has an expected lifespan that's around 10 years greater than his unwed brother. Women also benefit from wedlock, but not quite as much: they only get about 4 bonus wedding ring years.

One explanation for this effect is that single men (and women?) are more likely to engage in risky behavior that could cause a premature death. It's also possible that a good marriage provides emotional support and a sense of purpose that is powerful enough to extend a lifetime. Another conceivable factor is that the people who are most physically and psychologically "fit" for survival might also be the most desirable mates and therefore the most likely to get married, though this speculation is a lot more controversial.

It is important to note the difference between cause and correlation. Married people live longer and it's possible that marriage brings companionship, better eating, sense of purpose or some other set of factors that extend one's life. But it's also possible that people who are going to live longer anyway are more likely to be married. Perhaps more outgoing, health conscious, conscientious individuals (all lifestyle traits associated with longevity) are traits associate with a higher likelihood of getting married. Unfortunately most studies do not have the time or resources to isolate every possible factor so we are left with speculation. The fact is that if you want to live longer, research has shown that avoiding loneliness, eating properly, having a sense of purpose, etc. are all positive factors and may be helped by being married.

Longevity is not one of the reasons that people run off and get married but it is a nice side effect.