When the Oscar-winning film Forrest Gump was released to widespread acclaim in 1994, the veteran athlete Bruce Tulloh felt slightly disgruntled. “It makes out you have to be some sort of halfwit to run across America,” he complained. His son, Clive, a young witness to his father’s own transcontinental voyage in 1969, replied: “Dad, why don’t we have a look at that sentence?”

Tulloh’s decision to run 2,876 miles across the United States was based largely on a whim and the Guinness Book of Records. Leafing through a copy given to one of the athletes he coached, Tulloh was intrigued by the story of Don Shepherd, a South African who traversed the nation in 73 days, carrying a backpack filled with a plastic mac, a…