I think a long lifespan is hereditary.
My grandparents and now my parents and aunts and uncles are hitting the mid eighties. My grandparents and their siblings on both sides of my family hit the 90/90+ mark. I don't expect to make it as long as they did because I smoke and have all kinds of nasty habits that are supposed to kill off a person. But so did they. George Burns smoked cigars until he was a 100 years old and it didn't hurt him much. I don't exercise except for long walks when I go to Las Vegas, I take medicine every day and I'm overweight. I eat red meat with every meal, never eat chicken or fiber foods, hate vegetables. My hair is still without a single grey hair while all my friends are scrambling to color theirs. I don't have any wrinkles, bags or sags. I look like a teenager compared to my spouse who is only eight years older than me and already looks a 100 years old.
None of my sisters or brothers have grey hair and they're older than me. None have wrinkles.
I noticed when I hit the 40 year old mark that I aged. It is only when I look at my hands that I can see myself as being an older person as they are starting to shrivel.
I think diet and exercise as well as lifestyle can make us live healthier but I'm not certain it makes us live longer. Scientists say exercise adds two years to a person's lifespan and then turn around and admit it is because of men working as laborers which causes them to have a shorter life expectancy than women, so I am not sure exercise does all that much.
There's a website called livingto100.com that has a life expectancy calculator with no strings attached. According to the calculator, I will only make it to 73. When I do the test for some other members of my family who are in their eighties or nineties it says they died already

so I am not sure how accurate it is. The website is presented by the Alliance for Aging Research so I suspect they study our answers.
I think by living dynamically we increase the quality of our lives but I am not sure we increase our actual lifespan. I suspect that it is genetic, however, with myself, I think I may have shorted my predetermined lifespan by smoking and that I may very well not make it as long as I would have if I had made a few healthier choices along the way.