Sean Donnelly competed in track and field for only one year in high school before going to college. He studied Exercise Science at Mount Union University and then Kinesiology in graduate school at the University of Minnesota. He says his success as a thrower, on some level, has come from his fascination with physiological science; he understands what his training does to his body. He is the son of Stephen and Joyce Donnelly, and he has two siblings, Maggie and Steve. He’s a devout YouTube vlogger, documenting his four NCAA Division III titles and collegiate record. The videos on his channel date back to 2011.