Our state of arousal--being fearful, agitated, or calm--can significantly affect our ability to make optimal decisions, judgments, and actions in real-world dynamic environments. Imagine, for instance, walking across a balance beam. Your performance--speed across the beam and the odds of making it across without falling off--are dramatically better if the beam sits a mere six inches off the ground and you are relaxed rather than terror-stricken on a beam 60 feet higher. To keep you in the zone of maximum performance, your arousal needs to be at moderate levels, not so high that it pushes you over the edge.