Even when faced with an incurable illness, positive feelings and thoughts can greatly improve one’s quality of life. Dr. Wendy Schlessel Harpham, a Dallas-based author of several books for people facing cancer, including “Happiness in a Storm,” was a practicing internist when she learned she had non-Hodgkin’s lymphoma, a cancer of the immune system, 27 years ago. During the next 15 years of treatments for eight relapses of her cancer, she set the stage for