View it as training and not exercise. You start minimally and slow, far below exertion capacity, rest a few days, and do similar stuff with slightly more inten

View it as training and not exercise. You start minimally and slow, far below exertion capacity, rest a few days, and do similar stuff with slightly more intensity (resistance) or volume (number of reps). There's an art/science to it, and barring health handicaps it's essentially a universal system the body evolved to do.