Spend your time and energy doing what is important to you, rather than worrying about it. Focus on your plan of action. Ask yourself questions to bring your mind back to your task. Develop your powers of visualization. Any type of performance can be improved through repeatedly visualizing success.
Visualization is part of strategic training for many athletes.
A combination of practice and visualization has been shown to be significantly more effective than practice alone. While any library or bookstore will have a variety of books and tapes you can use to practice relaxation and visualization, you can also create your own routine. Give yourself time to relax. See yourself handling the situation as you will when you have overcome your anxiety. Your visualization needs to be reasonable and believable.