Breathing exercises! the alexander technique is great. Its used by a lot of actors and singers for the breathe, but there are great techniques to learn for anyone. Sometimes we really need to reach out to someone and ask for encouragement, because when we don’t believe something about ourselves, we will believe it when we hear it from others. maybe try to find an accountability partner, and ask them if they can give you encouragement before an event to take away the nerves? Preferably someone older and wise. that works for me.