O'Brien was born in Portland, Oregon in 1966. He is of African American and Finnish heritage, and grew up as an adopted child in an Irish-American family in Klamath Falls. He graduated from Henley High School in 1984 and then attended the University of Idaho in Moscow, where he competed in track and field for the Vandals. After initially flunking out of the university and then incurring legal difficulties, O'Brien attended Spokane Falls Community College, a community college in Spokane, Washington in 1987-1988. He returned to the UI to compete for the Vandal track and complete his bachelor's