When we encounter a stressor, our nervous system activates the "fight or flight" response. Stress hormones like adrenaline and cortisol are released, preparing the body for immediate action: the heart beats faster, breathing quickens, and muscles tense. This mechanism was vital for our ancestors' survival. However, in the modern world, where stressors are mostly psychological (work problems, financial worries), this response often goes without a physical release, leading to chronic stress.