I've had nine concussions, eight of which came through "legitimate" means ie: doing something crazy. The ninth came from lightly bumping heads with my 3 year old son. Got it just right in the spot where I'm most vulnerable.

I can tell you that I'm terrified to hit my head. If I accidentally bump it or brush up against something, the panic that washes over me is palpable. Just this past Saturday I was at a wedding, and a server absolutely drilled me in the back of the head with a full plate. I was ******, and I was really paranoid that the familiar concussed feeling was coming up next. It didn't, but living in fear is brutal.