Dr. William Glasser, a psychiatrist from Los Angeles, made a study of regular, long-distance runners. He found that those who practice a personal discipline for a regular, lengthy period of time gain psychological benefits. They do not suffer from spirit-breaking depression, anxiety, or worry when difficulties, even traumas, come up in their life. They are strong enough not to be driven by pain to self-destructive behavior. They possess strength to take care of themselves through learning how to handle tough situations in their chosen discipline. Dr. Glasser calls it "positive addiction."