If you want to do some exposure therapy, there are safer ways. Do things that cause contact with your head that will not cause a concussion. Open the freezer then push the freezer door open the rest of the way with your head. Have people touch your head, lightly at first then with a bit more touch. Not a hit, though. Eventually, a touch can become a tap, and so on. Fall back in bed onto your pillow.

There are a lot of things you can do that do not have the high risk of a skateboard.