Too much exercise is also injurious. That said, I have subjectively experienced an adrenaline rush for stupid reasons and chosen to do nothing with it — no run, no fight — and the subsequent downer felt terrible; as a result of this, I assume that physical exertion produces extra substances in the body which mitigate the stresses in much the same way that purely psychological stress is countered with external substances such as alcohol, weed, etc., or clinical antidepressants.
Really interesting point. Body gets all charged up and then needs to work to eliminate byproducts through slow manual processes instead of them being excreted through exercise. That would make a lot of sense.
