I’m all for good self-esteem but if you’re not completely satisfied with the amount you have, you can still be an effective speaker.
The point of getting over yourself is to remove yourself from the mix get out of the way. When you do that, your self-esteem isn’t an issue, because speaking isn’t about you.
Removing yourself from the mix involves focusing on the idea and how it will help the audience or why they need to hear it and realizing that the idea is more important than you are.
If you make mistakes, stay focused on helping the audience (rather than what they think about you) and you’ll get the job done. And, as you trust that, you’ll see that your speaking is being well-received and the ideas acted upon.