Marioair
I used to race cars in my early 20s racing in formula ford, clubmans and formula 3.
The nerves you got before a race could be awful especially lined up waiting to go out onto the circuit.
As soon as the lights changed to green all the nerves and anxiety went.
You do not say whether you are a PPL or Student or the level of your experience.
Most fears are of the unknown or something you are not familiar with! The more you fly the more normal the whole thing becomes and the more relaxed you will get.
With any fears some are genuine some are what ifs and negative thoughts about what you are about to do.
Try and identify those negatives thoughts and replace them with something positive to you.
If its a fear of not impressing your instructor/Examiner see him as a mere mortal with his own problems and tell yourself if I mess up I mess up! so what?
Same with the flying whats the worst that can happen you get killed so what ?
You will no longer have to worry about paying the bills or the wife etc
Anyway your superior skills will see you through
Talk to yourself and the aircraft. "I am going to enjoy this even examinations".
As for the aircraft??? " You damn B*tch I am in charge here you will do what I say "
Above all accept some nerves are normal and enjoy it
Pace