Fear, anger, and anxiety-the side effects of life's everyday stresses-are natural and sometimes helpful, but left unchecked they can lead to a host of debilitating ailments that are now so common we assume they are unavoidable: heart disease, arthritis, gastrointestinal problems, depression, and more. There is good news, though: The key to a healthy life free of these conditions is to activate what Harvard Medical School instructor Dr. Eva Selhub...