Stress is simply the body's non-specific response to any demand made on it.
Stress is not by definition synonymous with nervous tension or anxiety. The important thing to remember about stress is that certain forms are normal and essential. As the body responds to various forms of physical or psychological stress, certain predictable changes occur. These responses to stress will occur whether the stress is positive or negative in nature. Continual exposure lowers the body's ability to cope with additional forms of psychological or physiological stress.