Stress is simply a reaction to a stimulus that disturbs our physical or mental equilibrium. In other words, it's an omnipresent part of life. A stressful event can trigger the “fight-or-flight” response, causing hormones such as adrenaline and cortisol to surge through the body. A little bit of stress, known as “acute stress,” can be exciting—it keeps us active and alert. But long-term, or “chronic stress,” can have detrimental effects on health. You may not be able to control the stressors in your world, but you can alter your reaction to them.