Hi there,
This might help. In situations like this I imagine myself as a character acting out a part. Pretend you're in a book, movie or game or something. I do this all the time. Base yourself on a character you think suitable. I find this helps keep my mind off being scared of an attack and so helps me prevent any anxious thoughts.
I wouldn't recomend carrying this role play into your personal life though. As that would be cheating everyone, and yourself, from the real you. But in public situations, esspecialy a job like yours, I don't see any harm in it.
Take it easy :)