Using rehab exercises and/or stretching is a very helpful low impact strategy when not feeling well enough to hit the gym, go for a run, play your sport etc. When feeling under the weather, doing 10-20min of stretching, maybe only one area, like the shorter hamstring, or doing a few sets of wall angels, can be an amazing way to make yourself feel better with very low effort. It works really well as if done properly it’s that mindfulness or maybe more like bodyfulness required to do these (like in yoga and Pilates), that necessity to be really present and feel the areas of the body in focus, that can give you that pleasant feeling some of us know and appreciate from exercise.

Little tip, the more often you do these, the easier it is to get into that mind/bodyfulness state, and additionally you get visible feedback in the form of more flexible body and more self body control. Find your weaker spots, and enjoy working with them, till they are not weaker anymore.