Or, could it be that when you push to perform, your adrenaline levels and cortisol levels increase ? Both are part of the anxiety/fight/flight system.

I know that certain activities will leave me a bit hyper or anxious or stimulated, however one defines it.

Maybe increasing your serotonin levels will help. A 50 mg or 100 mg 5-HTP capsule each morning may help. It has changed my life. I no longer take the SSRI I took for anxiety for 14 years. I replaced it with 5-HTP and feel much better. 50 or 100 mgs of 5-HTP is very safe unless one is taking an SSRI.

But, I also know to not stack strenuous activities on top of strenuous activities.