Flight or Fight
While the body is preparing itself for action, the amygdala has fed its treat assessment to the thought-processing areas of the brain, which in a few seconds must decide whether to run away or take action, the "flight-or-fight" response.
After assessing the threat, the brain may decide it is minor, judge it an acceptable threat, and embrace it, such as the fear you experience when making your first parachute jump. After a fearful experience, we have a feeling of relief and elation, so acceptable threats may actually be therapeutic. They allow the amygdala to engage and give one the "rush" of fear without the accompanying danger.
So in a self-defense situation, when you feel cold, turn pale, get goose bumps, your pulse rate increases, and you begin to tremble, it is not because you are unduly fearful, it is the natural response of your body preparing to either flee or fight. Taekwondo training teaches students to deal with their fears, accept their bodies' reactions to fear as normal, and to take the proper actions to deal with a threat. Everyone, even a world champion black belt, feels fear in a dangerous situation. It takes courage to face what caused the fear and prevail over it. Courage comes from the skills, knowledge, and confidence gained through Taekwondo training.