The fight-or-flight response wires our brains to look for what’s wrong – a useful mechanism that kept our ancestors alive. But this same reaction firing due to fear of public speaking reflects a bug in our operating system, as 99% of our post-modern, first-world triggers aren’t actually dangerous.
To re-wire your brain, train it to look for what’s beautiful, what’s great, what the most positive attributes in others are. Many times per day. This is not a happy thought. In the same way your muscles won’t strengthen by doing a single pull-up once, this is a skills-based attribute that strengthens with daily practice.