most physically painful as a child was when i was 10 or 11 and i was at an after-school basketball rec legue paractice. i was running after a ball, dead sprint with one other kid and the chinup bars on the side were still set to 6-year-old height. i was looking down at the ball and my head went right into the side of the chinup bar. totally didnt see it. feet kept going, smacked down square on my back, blood coming from the scalp.