I think it's partly because as it also works as prevention of those same mental illnesses, many patients will have a higher than average barrier to clear to exe

I think it's partly because as it also works as prevention of those same mental illnesses, many patients will have a higher than average barrier to clear to exercise (including just getting out of the house for a walk). I've had friends able to start exercising a few months in their treatments, when the medication gave them more mental leeway. Before that they were fighting to wake up and properly eat, and do anything really.