Neptunus
Oooh, good thread topic!
I'd say around 13-15. One day I just became really self-conscious about sounding "stupid," even around friends I'd known for years. It all went down hill from there - to the classic symptoms like feeling like everyone was looking at me when I walked into a room, or whenever someone laughed it was because of me. Awful times!
I'm so glad that I've finally gotten past that. I credit age, experience and my job - it's very social, and has given me a lot of exposure.
I still have anxiety, but I've come a long way. I'm pretty functional.