Stress is an important concept in health psychology and behavioral medicine, but it proves somewhat difficult to define. So, stress can be defined as a complex transaction between a particular individual and a particular environment that takes place when the person is threatened or challenged. These demands can be experienced as positive, as when someone poses to us a challenge that we enjoy meeting: “Would you like to go out with me?” Positive stress also called Eustress- gives us the opportunity to satisfy our need for mastery as well as many other motives. Demand can also be experienced as negative. Negative stress- that is, distress- disrupts our life, leading to anxiety and depression, poor health, and even death.