What is a healthy AND fit body as an 80 y.o.? For me it should be able to help me do what I wish to achieve in life -- which means not only able to take care of my physical needs from carrying groceries (often 20+ lbs) from grocery store to bus to subway and then from there to bus stop to my apartment, with a few stairs up and sown. (Yes the cat litter box is 7kg=15 lbs) Ability to walk briskly for 30 minutes or more. And hoover the apartment, walk up/down in my building 10 plus floors tells me I am good enough. Never weighed, nor need to...if I get a pinch at my waist below it's less than half inch, so no Excess fat. Feeding body wholesome simple tasty foods and ensuring it's limber enough is all I care for to help me then focus on doing what matters to me in my life, aka, purpose.

I wish you a physically strong flexible body that has a mentally healthy state.

P.S. Yes I make my lovely senior cat run around and jump down from the kitchen shelf 5 times before getting his food. Too many pets in apts get little exertion.