 Heckendorf was born in Wausau, Wisconsin where he grew up.He played high school football for Mosinee High School in Mosinee, Wisconsin, as a wide receiver and a safety.As a junior, Heckendorf was named first-team All-State by the Wisconsin Football Coaches Association (WFCA) and second-team All-State by the "Associated Press" and the "Milwaukee Journal Sentinel" after he set state records with 116 receptions for 1,714 yards and 11 touchdowns.