No matter how much you have prepared there may still come a time during the exam that you start to panic or need a break. Make sure to take the breaks when given, or when you feel like you are tensing up. Take a couple of seconds to regroup. Remember to stay calm, regroup and refocus so that you can continue on with your test.
In combination with the visualization, make sure to work on breathing.
Breath in for four seconds 1.... 2.... 3.... 4....
slowly let your breath out for four seconds 1.... 2.... 3.... 4....
Make sure to relax those shoulders. Do this multiple times just to get back in control to move forward.