Actress, author and singer Olivia Newton-John, 71, is battling breast cancer for the third time. "I'm happy. I'm lucky. I'm grateful. I have much to live for. And I intend to keep on living it," she tells "CBS This Morning" co-host Gayle King in an emotional interview at her Los Angeles home. Newton-John talks about her diagnosis two years ago and how, while the pain can be unbearable, her spirit remains unshakable.