“Tough Old Man” by L. Ron Hubbard
Publication date: November 1950
Original publication: Startling Stories
Genre: Science Fiction
Story description: A Frontier Patrol trainee, sent for grueling testing on planet Ooglach, is about to fail when he finds the willpower to go on and discovers a secret that secures his future.
Currently available as part of the Stories from the Golden Age series, in the title When Shadows Fall.