Adrenalin is a hormone which increases heart rate and blood flow and prepares the body to either defend itself or to run--what is often referred to as fight or flight. Many times athletes want to trigger an adrenalin rush just before a contest to give themselves as much of an edge as possible. Frequent adrenalin rushes can be stressful to the heart.
Visualise a past situation in which you were extremely frightened. Try to relive the situation in your mind--visualise every sight, every smell and every sound that made you frightened.
Visualise a situation in the past in which you were extremely angry. The more vividly you can recall this situation the better. Let the anger flow through your body now.
Relive a stressful situation. Try to recreate the stressful feelings, recalling situations, lines of dialogue and anything else that caused you to feel as if you wanted to explode--or scream or run away.
Clench your fists and make grunting noises while forcing air through your mouth or nose in order to "get yourself psyched."
Once you have created an adrenalin rush use it quickly as adrenalin is a short-acting hormone designed to provide a short burst of energy for the body.
Do not create adrenalin rushes on a frequent basis as this could cause permanent heart or circulatory damage.