Firstly, I think the better way to describe what you are wanting less of, is being less of an introvert. Shyness is to the point that social/physical contact is unbearable, and may be misdiagnosed as "Antisocialism" or "Autism".
A good way to start, is to point out what makes you an introvert compared to others. Are you scared by how you might be judged? Are you simply a thinker, rather than a brash "voice"?
Try saying things such as "I express my thoughts freely" "I am powerful" and other statements that can boost your esteem when it comes to social outlook.
Then again, there is nothing wrong with being introverted. Sadly, American society does not see it that way. They prefer extroverts; people who speak freely and can act in a crowd.