You might recall past studies of elite atheletes that showed a sizable correlation with increased life expectancy:

• Atheletes Live Longer, Probably the Exercise
• Putting Upper Bounds on Longevity Derived From Exercise

Exercise and physical fitness are obviously things to point to here. Causation is harder to pin down in human studies: for example, we might ask to what degree competitive athletes are drawn their line of work because they are more robust than the average individual - and thus capable of living longer anyway. While it's certainly the case that a mountain of studies show causation for health benefits deriving from moderate exercise, there isn't as much to point to when it comes to the same for human life expectancy. There is certainly a lot of correlation in published research, however.

There are any number of other significant factors at play here when you look at statistical differences of a few years up or down in human life expectancy. For example, wealth: successful professional athletes are wealthier than the average fellow. To what degree is their longer life expectancy the result of the broad array of benefits that come with being wealthier? Easier access to medicine; more personal connections where it matters; greater likelihood of education or other access to knowledge that helps with taking advantage of medicine; and so forth.

Here is another study that shows a longevity advantage for athletes, but which unfortunately doesn't help much with questions of causation:

Olympic medalists stay alive longer, study finds

Athletes who win at the Olympics may bring home more than just a medal: They could add a few years to their life spans, scientists have found. Winners of a gold (or silver or bronze) medal lived almost three years longer on average than their country's general population - when matched for age, gender and birth year - according to a study [that] examined some 15,174 Olympic medalists.

"Some elite sportspeople may be influenced by fame and glory, which could confer longevity through increased affluence," said an editorial accompanying the research, "unless undermined by excessive partying and hazardous risk-taking behaviors."

Alternatively, survival edges could simply be due to more healthful lifestyles and physical fitness. [Researchers] said it wasn't possible to examine the longevity fates of those who competed in the Olympics but did not win a medal because records for non-winners weren't nearly as complete as those for winners.

The study is open access and very readable, so head on over and have a look at the published paper. It isn't the first to suggest that high intensity regular exercise is either no more beneficial than moderate regular exercise or no more correlated with longevity:

Our results show that former Olympic athletes who engaged in disciplines with high cardiovascular intensity had similar mortality risks to athletes from disciplines with low cardiovascular intensity. This would indicate that engaging in cycling and rowing (high cardiovascular intensity) had no added survival benefit compared with playing golf or cricket (low cardiovascular intensity).

Source:
http://www.fightaging.org/archives/2012/12/life-expectancy-in-successful-atheletes-is-a-good-example-of-why-its-hard-to-pin-down-correlations-in-human-longevity.php