When a person is confident,they walk "tall", stand straight, look people in the eyes, all while breathing evenly. What? You say you can't do that? Could it be that you just don't know how? Why not get that knowledge. How? Practice. Repetition is the mother of success. Practice in the privacy of your own home. Smile while you are at it. Life is like a mirror. We get the best results when we smile at it. :)