The brain is harder for us to understand than a femur, but that doesnt warrant dismissing its malfunctions. Exercise, good sleep and similar stuff is healthy for everyone, but suggesting healing OCD with that is just as ascientifical as suggesting to tough it out for a broken bone.
For example, if you have depression, doing sports most certainly help you get out of depression. If your body image makes you depressed somewhat, sports fix that. (Put aside cases where people have a burned face or some other irregular case.)
For OCDs, you may get your obsessive thoughts/actions to be replaced by sports activity. You exert energy, you work and it helps.
That said, physical activity, when carefully engaged in, is a great clearing agent for brain fog. Get to the gym, or go for a hike, jog, swim, or bike ride, if nothing else.
See how that sounds?