Health psychologists examine psychological influences with regard to how people stay healthy, why people get sick and how people respond when they become ill. For example, they examine which behavioral and social factors contribute to health or illness. The focus is on the prevention and treatment of diseases. Promoting a healthy lifestyle plays a role in this. It is important to keep an eye on the definition of health. Rather than defining health as the absence of illness, health is recognized to be an achievement involving balance among physical, mental and social well-being. Throughout history, the interaction between body and mind has been an important subject of research for philosophers and scientists. The ancient Greeks were among the earliest civilizations to identify the role of bodily factors in health and illness. Before the ancient Greeks, in prehistoric times, disease was thought to arise when evil spirits entered the body. By the Middle Ages, the pendulum had swung to supernatural explanations for illlness. After that, during the Renaissance, great strides were made in understanding the technical bases of medicine. This could be done because of the development of the science of autopsy and the invention of the microscope.The biomedical model resulted out of medical practice and has been used as a guideline for the past 300 years. This model assumes that psychological and social processes are largely irrelevant to the...