Probably breaking my wrist at the age of 15. I came off a skateboard at full speed & heard the bones in my wrist snap followed by the worst pain ever. I had to have the bones reset & my hand & forearm in plaster for at least 3 months. I also hit my chin hard when I fell & had x rays because they thought I'd broken my jaw as well. The only consolation was finding out my jaw wasn't broken. I'm naturally right handed so I found having to do everything with my left hand for months hard to cope with.