I have just read a book called NLP & Sports. Anyone familiar with Neuro-Linguistic Programming will know the sort of things that are covered: visualisation, positive thinking/words, etc.
One very insightful observation in the book is that, physiologically, anxiety and excitement are very similar. BUT with the latter you breathe deeply and freely.
So, next time you are in a stressful situation, try breathing deeply for a minute or so (at least 5 seconds in and 5 seconds out) and see how it affects how you feel.
If you have positive thoughts at the same time (think of your successes, happy times, euphoric experiences, loved ones etc.), this will help even more.
Agree? Disagree? Let me know.
PS: You can see my full reading list and book recommendations on LinkedIn