As a teen, Keith joined the Civilian Conservation Corps and served in Elgin, Oregon, building roads.
He enrolled at Cornell University after the war on the GI Bill and graduated with a degree in English, with an eye toward being a writer.
He found a job as a laborer on the Kodiak Naval Base, and there met Richard "Dick" Proenneke, who was working as a diesel mechanic.
After several years, Keith returned to Massachusetts in the 1960s, where he married and became an English teacher at Silver Lake Regional High School in Kingston, writing on the side.
Keith wrote One Man's Wilderness: An Alaskan Odyssey (1973) based on his lifelong friend's journals and photography.