Stress is the body's response to any demand placed on it, whether caused by external or internal factors called stressors. There are three stages of stress - alarm and mobilization where the body goes on high alert, resistance where the body adapts to stress, and fatigue/exhaustion. Chronic stress can occur when demands never stop and a person feels they have no way out of a miserable situation. Anxiety disorders are characterized by feelings of anxiety and fear about future or current events and include panic disorder, social anxiety disorder, specific phobias, and generalized anxiety disorder. Athletes can experience both physical and mental anxiety that negatively impacts performance.