Stress is for many of us the beast waiting in the wings, because it's a healthy adaptation to your environment -- you run rapidly away from a saber-tooth tiger chasing you. But chronic stress historically was really only seen in one major condition. That was famine. So it allows us to survive under harsh conditions, but it's not conducive to living a long life with the kind of vitality we want. It's designed to get you through a crisis, and, therefore, when we have chronic stress occurring in modern day life -- because you've got credit card debt or because your relationships aren't going the way you want them to go or because you've got chronic pain or you're depressed -- then these all become factors that slowly stress out the hypothalamic pituitary axis. This is the part of your brain that connects down to your adrenal glands. It allows you to cope with stress but it eventually gets taxed out and you short-circuit. And then you start to slide down the hill, and it's very difficult to go back up again unless you completely reboot yourself.