This document discusses stress, what it is, and its effects. It defines stress as a normal reaction to events or thoughts that make one feel anxious or frustrated. Our thoughts about situations, not just the events themselves, determine whether we perceive something as stressful. Stress can be positive in small amounts by motivating us, but too much stress can harm our health. The document outlines common sources of stress including the environment, social roles, physiological factors, and thoughts. It also discusses signs of stress overload and various physical and mental effects stress can have on the body and brain.