There's a section in the book, Blue Mind about how we evolved to deal with stress in intense bursts like getting chased by a predator. This is the Red Mind fight or flight. It keeps us alive and give us that burst of cortisol to survive then we chill the rest of the time. Modern life puts us in Red Mind/ stress mode 24/7 with busy schedules, bills, work we don't like, etc so we never get that break. We have to make time to chill!