Research with tens of thousands of people showed that it wasn't weight, alcohol consumption or even whether or not you smoked that was the greatest predictor of how long a person lives. In second place in the top ten factors that contribute to health and long life is close relationships, people you can rely on and talk to. In first place as in, the number one predictor of health and survival is the range of both strong and weak connections a person has, ie the extent to which they chat to people day to day - the person in the coffee shop, the cleaner at work, your neighbours. Conversely, not interacting with other people day to day, not having incidental conversations with people, has a massive impact on health. It is the primary factor that makes the difference.
This is an excellent talk about the effect of relationships on health, I'd recommend watching it: www.ted.com/talks/susan_pinker_the_secret_to_living_longer_may_be_your_social_life/transcript?language=en