[khazhou]

I suspect your starting point was different than OP's. He is describing (I think) a crippling nervousness. This is very different from just tensing or run-of-the-mill nervousness.

All your advice is great, but (from personal experience) it's not enough to overcome phobia-level tension.

I think many people don't understand what phobia-level tension even looks/feels like. My own worst moment: presenting an architectural diagram to a VP, I started panicking, and repeated the phrase "...and we're going to build an abstraction layer..." three or four times in a row, in a slow monotone voice, until someone in the room snapped me out of it. Embarrassing is an understatement.