Through our lives, most of us develop what can only be called a deeply personal relationship with our anxiety. There’s a good reason for this. A predilection for anxiety was built into our neurophysiological wiring as a kind of evolutionary early-warning system for us hominids in an unpredictable, often hostile environment. Anxiety, in this sense, is like a loyal, somewhat skittish guard dog—maybe too easily aroused, but handy to have growling around the cave when intruders threaten.