According to this study, if you feel anxiety before a public performance (e.g. an interpreting assignment), turning that feeling into EXCITEMENT (i.e. 'this is an opportunity' or 'a challenge') is more helpful than telling yourself to calm down. Excitement is a similar emotion, whereas calmness is the opposite.
http://www.theatlantic.com/health/archive/2014/01/study-fight-performance-anxiety-by-getting-excited/282886/
http://www.theatlantic.com/health/archive/2014/01/study-fight-performance-anxiety-by-getting-excited/282886/