I remember one time when I was a young kid and yo-yos were a craze.  I tried to learn all the tricks and then there was a competition at the mall.  I told my dad I didn't want to participate because I wouldn't be good enough.  Then I saw how they started with basic tricks and I could easily do half of them and would have gotten a prize.  I missed out and I knew it.

Don't ask me how I remember such an insignificant moment but it pops into my head whenever I hesitate to do something out of fear of losing.