This reminds me of the common phrase "Use it or lose it", which can apply to a lot of different things. When it comes to our bodies, exercising the muscles is the topic. Whether it is challenging the brain, or moving the different parts of the body, those are needed to keep the mobility and sharpness. I think we can all think of a way to improve our lives a little. One can start small and slowly build on it.
Exactly - and we used to use it all earlier, and for much longer than we do now - these days, we are sedentary in just about everything that matters.