I'm sure I read somewhere that the proportion of time that a species spend as dependent infants is related to their potential longevity. Which shouldn't be interpreted as putting off potty training till you are 35 will let you live into your 90s. Though if you live that long, you might be back in nappies.
It's best to think of genes are bracketing possibilities; a little short-legged chap like me isn't going to chase down Usain Bolt* and steal his chips, but equally, I – through effort and training – can learn to run faster. And environment counts more than anything. If I challenge Usain to side by side 100 m race, and he gleefully accepts, but then flood his lane so it's knee-deep with treacle, little short-legged me, unencumbered by the sticky stuff, will claim that sultry bag of steaming chips and have eaten them before he gets anywhere close.
So, basically, some genes (probably thousands) will affect your lifespan, but you also have to survive long enough to encounter those effects. Obviously, there are a few things based on single gene effects, like Huntington's, that can put more firm punctuation on a lifespan. Of course, genes that are positive when you're young (so are heavily selected for) may be negative when you're older, and potentially vice versa.
So basically, we're left with boring old eat your greens and do your exercise, avoid tigers and serial killers, and wish upon your genetic good luck.
*I have no idea if he likes chips, but I think everyone does.