Do you get nervous when you have to speak in front of a group?
Instead of allowing yourself to stay in that dialogue with yourself about how nervous you are, force yourself to turn your attention to and then dialogue with your audience.
Literally dialogue. As people are entering the room or taking their seats, and as you are gearing up and feeling those butterflies, start looking at and talking to THEM. Look into their faces, talk to them as if you are getting to know them.
Stop dialoguing with yourself about you and your nerves and start dialoguing with them about your content. It will shift your focus away from how nervous you are, and you will feel better. And no doubt, so will they!