Stress is the body's reaction to any change that requires an adjustment or response. The body reacts to these changes with physical, mental, and emotional responses.
Stress is a situation that triggers a particular biological response. When you perceive a threat or a major challenge, chemicals and hormones surge throughout your body.
Stress triggers your fight-or-flight response in order to fight the stressor or run away from it. Typically, after the response occurs, your body should relax. Too much constant stress can have negative effects on your long-term health.