Stress is a response or reaction to change. Many times, this affects you emotionally and physically.
Stress can be positive or negative stress.
Positive stress helps your body work more efficiently, improves your concentration, and allows you to do certain tasks better. Stress may be harmful when you cannot relax after meeting a challenge. When this becomes constant and a part of your lifestyle, your health may suffer. The concept of stress is personal in nature. We define stress as the perception of a threat to one's physical or psychological well-being and the perception that one is unable to cope with that threat.