Only on the "CBS This Morning" podcast, Dr. Dean Ornish joins CBS News Chief Medical Correspondent Dr. Jon LaPook to share tips on how to live a healthier life. His new book, "Undo It!: How Simple Lifestyle Changes Can Reverse Most Chronic Diseases," outlines how readers can eat well, move more, stress less and love more. Dr. Ornish explains how these lifestyle changes can also improve mental health and shares how they helped him during his own experience with depression and suicidal thoughts at the age of 19.