For instance, ive been in a few one way fights in my life, I've never hit anyone back. I remember the adrenalin rushing through my body and the fight or flight response gearing up, but my mind overcomes that and I usually end up talking myself out of it or someone else interjects.
But because I control the fight or flight I end up getting the shakes after the incident because I didn't fight back nor run away, since shaking is the physiological response to burn off the adrenalin.
Personally, I feel I'd have done a lot better in those situations if I'd acted on impulse and actually fought back. Hell even running away could've served me better aswell.