Being a trainer, coach or public speaker you have to realize that how well you perform is only a secondary issue.
The main interest that you should have in mind is the value that you deliver. If you are charismatic and flamboyant but your info stinks is of no good.
The mindset of great public speakers is this: "it's not about me, it's about how can I best serve my audience". Once, you get this, 90% of your nerves go away.
You are not on trial, you are a passionate person with a valuable message to offer. So, take yourself out of the equation and perform at your best, but keep in mind that the value you provide will make a difference in their lives.
And not lastly, I found a mantra that gets me in the best shape possible before a webinar... and it's this:
"It's showtime" :)))
As in, it's time to have fun, bond with my audience and deliver great content. You are, after all, talking about a subject that your passionate, right?
So, prepare well, enjoy yourself in the process and your audience will have a great learning experience!