The first is shortness of breath: we don’t have the same respiratory capacity we used to, and we run out of breath quickly, in ever shortening distances. The second concerns our joints: they aren’t as flexible as they once were and limit our mobility. The third obstacle is muscle loss: the more we age, the more muscle we lose!
The good news is that these obstacles are far from insurmountable, which means that we can very realistically hope to regain the respiratory capacity of our thirties, the joints of our forties, and the muscle of our youth; so long as we put in the necessary effort and consistency.
All we need is: