I'm 56, I train 3 times a week, stretch every day ( working on being able to do the splits ) and do interval running 4 to 7 days a week. I feel great, my mobility and the physical freedom I earn from stretching - I am never stiff - and recently a nurse told me she would have never guessed I was my age. She called me jacked . . . proudest moment in my life. I take tons of vitamins and eat plant based. I feel better than I did 15 years ago.
Fromm a longevity perspective, exercise ( movement ) is 50% of the game.
J