I think there is a way we can gain from the previous generation's experiences as few generations have before.
Lifespans have increased. In most countries, life expectancy is increasing. We have better science, better medical care, vaccines, treatments for diseases that recently killed us quickly, etc. We see people we know living to ages our parents would not have seen.
So we see what happens in ways our parents may not have. Sure, people had long lives before, but they were exceptional. Now, getting older is the norm. People whose lifestyles or genetics would have killed them by 60 are living to 75 and beyond. When I look around, I see the people who are active as the ones who seem to be living the best lives.
The brain is part of the body, and using it, as well as using the legs and arms and heart matters.
Luck has a lot to do with it - poverty, accidents, and genetics take things out of our hands sometimes. But the general patterns seems to be that you move and be active, or you slide away. I've seen athletic people develop dementia and go for years with it - not the best of fates. There are no rules or predictable outcomes in this random life of ours (I'm one of those people who believes nothing happens for a reason, although everything has a cause and effect). I am going to try to keep moving, even though I kind of like sitting on my butt with online entertainment like this forum, hate gyms and loathe exercise for exercise's sake. I still have to bite the bullet and get it done.
As a community, we just lost Byron Hoskings, a wonderful man who posted here until he was no longer able to. Through his long battle to stay alive with cancer, he seemed to want his normal, which was listening to people and trying to present his thought and experience to help them enjoy fishkeeping as much as he did. You have to admire a person like that, and maybe learn more than just facts about fish and nature from them.