____________ —the way a person ______ 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 _________ of people in the United States report that they feel more stressed today than they did 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 daily lives. Researchers at Rutgers University suggest that recent changes in people's ________ have caused more stress. Stress causes the body to experience physical changes such as a faster heartbeat and breathing rate. The right level of stress can make a person feel stronger and more energetic. Researchers believe that in the past, this ________ helped people to hunt for animals and to protect themselves from danger. They ______________ stress with physical activity involved in hunting, and then their bodies could ________ again. Although people today still experience an increase in energy in response to stress, they do not use energy like the hunter—gatherers did. As a result, it is more difficult for their bodies to let go of stress. Too much stress—or stress that continues for a long time—can cause serious physical and ___________ problems. These problems include trouble sleeping, sickness, and pain. Heart disease and even cancer probably result from stress. Moreover, people under stress are in more danger of having an accident at work or while driving, and they might start bad __________ more easily such as smoking or eating too much.