Accidents or crazy stuff can happen, but imho the most important key to longevity (other than good genes) is a positive attitude.
I have written often about my grandmother who lived to be 106.
That woman was always happy, smiling, friendly—even when “normal” people would be upset or angry.
Plus—she had amazing street smarts which she was kind enough to share with me as a young man—and I quote her often here.
One example: “Never believe _anything_ you see on TV.”
Another: “I don’t know what is wrong with these (90 year old) men around here—none of them want to dance.”
One of my aunts was like that, cheerful attitude and always smiling to light up the room. She too made it to 106. (must be a secret they had :>)
On the other hand, I overheard two of my uncles talking when both were in their 70s. One, who I always thought had the harder life, tells the other, "Well it's been a tough, sometimes hard life, but we'd do it again if we could, wouldn't we?
The other, who I thought had the easier life, responded with a somber tone, "No, I wouldn't do it again, there was too much heartache, too much pain."
Through the years, I've often thought that statement was the saddest thing I ever heard. Both men experienced the death of their first wives and tragic experiences with their children.
I think the difference was attitude--that cheerfulness that your grandmother and my aunt had can make life so much easier and evidently longer.