Journalist Katie Engelhart's new book, 'The Inevitable,' follows people who are planning to end their lives due to terminal illness or unbearable disability — either legally with physician-assisted death, or as part of the "euthanasia underground," outside of the law. "Most people who choose to end their lives at a preplanned moment are more concerned with things like dignity ... autonomy," she says. "They're worried less about the physical pain than the loss of themselves."