The virtue of all achievement is victory over oneself. Those who know this can never know defeat.
A. J. Cronin
It's been a long time since I read A.J. Cronin. Nice to see this quote just in memory of enjoying his books. Regarding this particular piece - I certainly believe it applies to achieving mastery and certainly mastery of public speaking. We overcome nerves, we develop "muscle memory" through rehearsal, we learn to interact with an audience rather than just speak at them, and so much more. What has been your greatest victory over yourself in becoming a speaker?
"You have to find something that you love enough to be able to take risks, jump over the hurdles and break through the brick walls that are always going to be placed in front of you. If you don't have that kind of feeling for what it is you're doing, you'll stop at the first giant hurdle."
-- George Lucas