>but many simply chose to not do anything to avoid the aging
Thank you for saying this. A depressingly large proportion of people are seemingly resigned to the fact that once you hit 40-50, you'll inevitably turn into an achy tub of lard and it's rapidly and irreversibly downhill from there.
Barring injuries that are truly irreversible (e.g. severe damage to joints/cartilage), with the correct diet and fitness regime, it's entirely possible to remain lean (≤20% bodyfat) and muscular (≥80th percentile in strength standards [0]) well into what most consider "old age." So many people have no idea just how poorly they eat or how inactive and physically weak they are, and consider the result to just be a normal part of life.
>I also write code daily, read the same things I read when I worked, thus keep my brain going too. You can't ignore body or mind, you have to keep both in tune.
Thanks for saying this too. So much cognitive decline is due to inactivity of the mind. My mom was whip smart until she retired in her mid-60s to a life of idle leisure, and her mental faculties noticeably deteriorated within a few months. Thankfully, she noticed this and deliberately re-engaged with more intense intellectual pursuits (including consulting part-time in the professional field that she loved), and the improvement was night-and-day.
[0] https://strengthlevel.com/strength-standards