At some point I think longevity is just in your bloodline. I have met someone that was 92 and smoked like that most of his life (starting in his early teens). I have also known people that died of lung cancer in their 40's because of smoking like that. Part of it is hedging your bets, part of it is eating well and staying healthy as you can. Some people just get a lucky card and can basically just do whatever they want as long as their diet is not shit.