I had that problem too and I'm trying to think back as to how I dealt with it. I remember my face getting really tense and I would go into the bathroom and massage my face which helped a lot. As far as being embarrassed, I look back on it now and think that I really cared too much what people thought, especially if people teased me (some were mean) or would ask "why are you so quiet?" I hated that question! Now my attitude towards that is... if they are asking that uncomfortable question, apparently me being quiet is making them feel insecure... and that's not my problem, that's their problem. Just like I have to manage my own insecurities, they need to manage theirs and not put that responsibility on me... and now I can smile and say because I am and walk away without carrying it around on my shoulders. Not sure if that helped at all.