My mother _forced_ me to try out for drama. She said 'all you have to do is audition.. then I'll never bring it up again'. I can't tell you how much the thought of even going to the audition repulsed me, much less performing on stage.
At the audition, while waiting, I was hanging around the most friendly people I had ever encountered (ok, it was a bunch of girls that were actually talking to me). Suddenly the fear of being onstage was less than the fear of being lonely.
I went from being scared of walking down the hallway to being able to talk in front of large crowds. My Friday nights of soldering and programming turned into a different kind of fun.. a chance to socialize with others.
(btw I can't sing for the life of me.. the trick is to stand in front or next to people with a similar voice. If you have a decent director they'll do this automatically)