It's interesting to note that their state of anxiety or relaxation depended not so much on how much they knew the music, how well they were prepared, or how few mistakes they were making recently.
It had to do with one idea only - "How do I look in the eyes of others? In the eyes of my pears, my teacher, my future listeners, who may or may not know me personally, who may or may not be able to play the organ themselves. My piece doesn't have pedal part and her piece does, so I must be an idiot and a loser".
My students who actually dismissed these thoughts were more relaxed. They were only thinking, "Am I better than myself yesterday?"
I suggest you try this idea and you might discover that your anxiety diminishes when you stop thinking about whether or not other people like your playing. Instead, think, if you're improving.
If the answer is yes, you're on the right track.
[If the answer is no, take 10 deep breaths, slow down the tempo by 50 percent, and repeat the fragment 10 times or go for a walk].
Transposing Sequence in B Minor: ii42-vii7-i