## Metadata - Author: [[Kelly McGonigal]] - Full Title: The Upside of Stress - Category: #books ## Highlights - As Walter Cannon observed, a fight-or-flight stress response starts when your sympathetic nervous system kicks in. To make you more alert and ready to act, the sympathetic nervous system directs your whole body to mobilize energy. Your liver dumps fat and sugar into your bloodstream for fuel. Your breathing deepens so that more oxygen is delivered to your heart. And your heart rate speeds up to deliver the oxygen, fat, and sugar to your muscles and brain. Stress hormones like adrenaline and cortisol help your muscles and brain take in and use that energy more efficiently. ([Location 910](https://readwise.io/to_kindle?action=open&asin=B00OI5PGWU&location=910))