Musicians' anxiety

It isn't easy.
A musician can have two activities: teaching students and playing in concerts.
As far as teaching is concerned, there is no cause of stress besides the stress that comes from the anxiety concertning students' performances.

But when the subject is playing, the dimension is totally different.

Playing for an audience is a pleasure; the muscian makes music and people applaude his work. However, stage fright and anxiety can make a suposelly pleasant activity become a burdon. Why? Because they are so difficult to support.

Symptoms:
fatigue, fluttering or pounding heart, shortness of breath, tremor in the hands and legs, sweating, nausea, diarrhea, pupillary dilation, facial nerve tics, dry mouth, chest pain, stomach aches, headaches

Stage fright mecanism:
(1) I perceive or imagine the presence of significant others who are able to judge me
(2) I consider the possibility of my visible failure at a task
(3) I feel a need to do well to avoid failure
(5) I focus on my own behavior and appearance

Tips:
-be prepared
-practice performing
-perform usually
-know your performance space
-prepare your body: make sure you get a good night of sleep before the performance, take a nap, don't practice for hours the day of your concert, eat well (making sure you have a good breakfast, but don't eat a huge meal before you play, don't play on an empty stomach either), stretch your arms, neck, and shoulders to try to relax physically, breath slow, steady, focused
-stay in the moment
-the audience is your friend
-have fun!

My advice: believe you can do it. Motivate yourself by watching a previous recording in which you succeded.

Check these relaxation exercises

Sources: wikipedia, bloomingdale school of music