I just walk, and quite alot...and can't afford much else. But it seems to be enough, because if I need to make a run for a train approaching the station, my body still has what it takes for a burst of speed, running down the street.
Imho, so long as the body is fit enough to undertake our given occupation properly, and is able to sit for a decent amount of time in meditation posture without harming knees or back, what more is needed? Why worry too much about something that could, in the realms of possibility, shut down and stop working any day or hour, and in any case one day, definitely will?
Then the Blessed One, picking up a tiny bit of dust with the tip of his fingernail, said to the monk, "There isn't even this much form...feeling...
perception...fabrications...consciousness that is constant, lasting, eternal, not subject to change, that will stay just as it is as long as eternity."