His greatest achievement came in 1992 when he won the NPC Nationals in the heavyweight division-becoming the US national bodybuilding champion and obtaining the NPC Professional League card. Three years later he placed first among heavyweights in the Los Angeles Championships, where he was also given the gold medal for the overall winner. In 1984, Duffy became the overall winner of the NPC Southern States bodybuilding championships. Duffy's idol was bodybuilder Arnold Schwarzenegger. Duffy was an All-American in high-school football, and started to train as a bodybuilder during his teen years.
