My setbacks have mostly come from too much activity vs. knocking my head into something (knock on wood). But they have gotten less severe and somewhat shorter lived over time.
I usually cut back pretty far on activity, except for crying on the couch, crying on the phone to friends, crying on friends shoulders
Not sure that's the right answer, but i do think there's something to be said for listening to your body and resting. I found this blog a while back and remember her words when i have a set back.
http://allconcussion.com/2013/04/con...with-setbacks/
Helps a little, but I posted some pretty sad words during a relatively minor setback a couple weeks ago. Reason just doesn't reach me when i'm in such a funk. I just tried to tell myself all i really had to do that day was breathe, and that the world wants me around.