He has written over 30 books ranging from political memoirs to poetry while continuing to actively comment on ongoing American and global affairs, such as the Israeli-Palestinian conflict. The earliest-serving of the five living U.S. presidents, Carter is the longest-lived president, the longest-retired president, the first to live forty years after their inauguration, and the first to reach the age of 95. . Returning to small-town life in Plains seemed 'a monumental step backward,' she said later. On the other hand, Carter felt restricted by the rigidity of the military and yearned to assume a path more like his father's. Carter left active duty on October 9, 1953. Carter and Vice President Mondale were formally nominated at the Democratic National Convention in New York City. Carter delivered a speech notable for its tribute to the late Hubert Humphrey, whom he initially called 'Hubert Horatio Hornblower.'