
Nelson attended Riley County High School in Riley, Kansas, and played football for the Falcons. During his senior year at the quarterback position, he completed 62 percent of his passes for 1,029 yards and eight touchdowns. He also rushed for 1,572 yards, averaging 9.8 yards per carry with 25 touchdowns. He was named Flint Hills Player of the Year by the Manhattan Mercury[6] and was a two-time. In 2003, he played in the Kansas Shrine Bowl. He was also an all-state basketball player, averaging 17.2 points per game his senior year for the Falcons.
Nelson was an outstanding track and field athlete, and won a national AAU championship in the 400 meters as a 10-year-old. In 2003, his senior year at Riley County High School, he won the state titles in Class 3A in the: 100 meters, with a time of 10.63 seconds; 200 meters, with a time of 21.64 seconds; 400 meters, with a time of 48.79; and long jump, with a leap of 7.00 meters.