Glen Sharp's boxing career was a rise-and-fall story without so much rise in it. A sparring partner for light-heavyweight Hall of Famer Yaqui Lopez, he "retired" with a record of one victory and two defeats. A decade later, having come to understand how and why he failed as a younger fighter, he attempted a comeback. Told with heart and wit, his memoir is a treatise on boxing as both profession and purpose. Sharp uses economic theory to...