If you want to be great at something, you have to first be willing to be terrible at it.
Go ahead. Try the thing you hope to do and fail at it. And when you do, fail gloriously.
Then, congratulate yourself. You just got the worst one out of the way.
And now you can work on getting better.
Your first song, your first speech, your first meeting, your first race - these are all great chances to do poorly. And once you do, the journey to greatness has begun.