(via Survival in the City - Blog - David Galletly)
SHAKE OFF FEAR PHYSICALLY
Place the fingertips on your stomach just below the solar plexus. Breathe in deeply, press hard with the fingers and bend over forwards. Hold this position and count one-two-three. Now let the breath come out slowly and stand upright. Repeat this effective measure until you feel calmer.
This will reduce the tension in your head and allow you to concentrate.