This, past a certain age building muscle is damn near impossible so you have to have realistic fitness goals and less excess mass is probably the most immediate goal.Currently my goal is just less fat and more muscle than I had last week.
We've already seen a minor SHTF situation with Covid and it wasn't kind to fat people, so I'd say the leaner and stronger we can all get the better.
My place is big enough that I should be able to lay out a walking path and at least try to take a short walk daily and a longer one as time permits.
I've started doing tai chi to stretch out and loosen the old joints and I must say that after only a couple of months I can really tell the difference in my mobility and flexibility.
I have physical limitations that prohibit intense and strenuous exercise so I work within those barriers to try and improve my fitness.
My goal is to be able to get up and go to the fridge for a snack without making that "old guy noise "when I stand up.
I'll never be svelte but I don't want to spend my final years trapped in a fat suit.