I did that when I was 11 once. Church window. Some older kid
  closed the door in front of me and made mocking faces at me. I
  punched at him right through the glass. Hit him in the face too
  but he just got a bloody nose. I got a wrist slash from it. It
  was a few stitches - the only painful part was the needle for
  the anesthetic - shock thankfully had me laughing hysterically
  the whole time 'til the needle went in. Then I was all mr.
  serious. I learned my lesson that day. [also had biofeedback
  training a few months after that at a psychologist - helped me a
  lot -- starting to think they MIGHT have been connected
  somehow...] == Well, biofeedback worked for me, but I was an 11
  yr old kid. It had some guided meditation, making a computer
  noise go up and down with my mind; I think it was a few months
  worth. Had to practice. Wasn't perfect of course, but the last
  time I got that kind of angry was a few years later, getting in
  a fist fight with a fellow 10th grader. I felt "too old for this
  shit" as I sat in the principals office, getting into a kids'
  fight like that at 16, so I stopped. ==