There is one more factor that is even more important than healthy lifestyle and genetics that has an impact on longevity. Let me narrate my own experience with this.
My father was a vegetarian, never smoked but used to enjoy alcohol occasionally. He suffered with a stroke for the last two years of his life and died at the age of 73. His classmate who was very close to him and I used to call Uncle. Uncle used to enjoy alcohol everyday and was a chain smoker and frequently eat non vegetarian food. He is still alive and into his nineties. On the other hand my father-in-law was also a vegetarian, never smoked or had alcohol, had a perfectly healthy lifestyle and died at the young age of 45.
All three of them had good genetics as their parents lived to a ripe old age without much disease. So what is the missing factor here?
It is living with Awareness. Experiencing ease, stillness, peace and joy as one goes through life everyday. This gives a positive attitude, primarily an attitude of gratitude. To cultivate this, the first step I recommend is to learn to switch off the incessant mental chatter and allow the mind to rest quietly in the present moment. I mention present moment because our mental activity either concerns the past or the future.
It is not easy to be able to quiet the mind at first because of the conditioning it has gone through while growing up. When the mind quietens, one would find themselves being present in their body. This is called an Aware state of being, or a Grounded state of being, or being in the Present moment of thought free awareness.
There are many practices that you can use as a portal to switch to this state of quiet awareness from the usual restless, distracted and thinking state of mind. Some of the effective practices that I teach are, Focussed Gazing and Conscious breathing, Deep Crossing and other gently body movements in sync with the breath that I refer to as Energy Movements, Gentle flexing and stretching movements that I refer to as SelvanS 30 Yoga, etc.
You can find resources to learn all of these on my website or in the various articles that I have published on my Quora Profile or in my book titled Inner Alchemy.
In the beginning it is only possible to remain in this aware state for a few seconds. Consistent practice would gradually improve body awareness. One may find that this practice naturally corrects even the negative aspects of lifestyle and genetics and enables a life of flow and synchronicity despite adversities and hurdles.