Here's the ironic thing about stress: The human body has evolved to cope with it too effectively. When you suffer under a crappy boss—a stressful situation, sure, but hardly life-threatening—your body responds as if you're being chased by a predator. Stress hormones like cortisol, epinephrine, and norepinephrine spike, causing your attention to narrow and your body's inflammatory reactions to kick into high gear. This would help you avoid infection if, say, your boss bit you, but when continuously activated, inflammatory reactions can wreak havoc on your health, leading to increased risk of heart disease, stroke, depression, and diabetes. Chronic stress can even shrink your hippocampus, a part of the brain that supports learning and memory. In short: You need to calm down.
It is probably a bad sign that I completely forgot to post this piece I did for Outside Magazine about ways to beat stress.