" Yet wrapped in this sort of adaptation for change is the mechanism for growth, and it, too, is rooted in what we might call stress. This is the process at work in every long run uphill or in every set of bench presses that reaches for a new personal record. We build muscles by tearing them down, stressing them beyond their limits. The body reads this as a need for more muscle to meet these new conditions of your life, and so the body builds it. And this works the same way in the brain: brain-building chemicals build new cells and make existing cells stronger. Yet Sterling’s "

― John J. Ratey , Go Wild: Free Your Body and Mind from the Afflictions of Civilization