Tell yourself to stay calm, and try to listen to yourself. All that internal conversation will distract you from whatever is tough and give your subconscious some time to work it out. Deep breaths help too, as does confidence in yourself or in the success of the situation.
Have you ever heard of "mindfulness"? It is a wonderful practice, and if you are going through a continuously tough time, you might want to look into it. It is like the white collar American's version of Buddhism.