Senior year in college I trained for my teaching credentials. I was a mess the week before it was my turn to take over the senior high class of an urban school. I’d avoided public speaking for years and was freaking out like the protagonist of the Scream by Edvard Munch.
I observed the teacher from the back of class for three weeks as part of the process. He was fantastic and the students loved him. A tough act to follow.
As a psychology major, I used deep breathing and relaxation techniques over several days to hypnotize myself as I envisioned my first day teaching my planned curriculum. The day I took over the class, I was fearless. Butterflies, yes, but a little performance anxiety is okay.
I still use this technique to associate relaxation with delivery in advance of a high stakes keynote speech or major surgery. Either way you stare into a dark abyss. It also helps to learn not to be attached to outcomes.