Let's see...in the 1st grade I was jumpin' rope in the rain and fell down and scraped up my knees up pretty bad-- getting the asphalt pieces from my knees didn't feel too great! That left my knees all scarred up.
A couple times after ballet classes around 2nd and 3rd grade- I was running around and fell down...my bloody knees got to dry up with my leotards on...that was a hell of a time getting those off.
Around 8th grade I pulled my back. That hurt like hell. Ever since then, I've been prone to back pulls.