Sometime between claiming my first Social Security check at 62 and signing on with Medicare at 65, I heard an offhand comment by a fellow writer on running from the same age-group. Rich Benyo, editor of Marathon & Beyond, had finished writing his life story and urged me to get going on mine. "Our age is the best time to write memoirs," he said. "We're old enough to have had the experiences, but still young enough to remember what they were." My second...