Stress - the way a person responds to changes and difficult situations - is a common experience that people all over the world share. In fact, most people have stressful experiences every day. However, research shows that people experience more stress today than they did in the past. Forty-eight percent of people in the United States report that they feel more stressed today than five years ago. In addition, most doctor visits in the world (three out of five) happen because of problems related to stress . Scientists and health workers are interested in this subject because high stress levels have serious consequences that can affect people’s health and their daily lives.