The real problem is we didn't actually evolve to live much beyond 40; we have scientifically made it possible but that isn't evolution. Our bodies reduce production of many important substances from the age of thirtyish - including creatine. If we want to live life to the full in old age it's likely we will need to supplement even healthy diets. I could probably live just as long sitting on the sofa watching daytime TV without though, but I wouldn't be doing all the things I intend to do till I kick the bucket.
Having said that, tendon and muscle repair does get much slower no matter what we do. So, as old age approaches, physical caution is important too (I keep forgetting that

).