Murphy went on to compete internationally as a powerlifter, and is currently training for the 2012 Paralympics. In 2008, The Paralympic Committee teamed up with Nike, which recruited Murphy to do a commercial for its "No Excuses" campaign.
In July, Murphy was contacted by Project VisAbility, an organization that finds fitness jobs for people with physical challenges. Thanks to the group, Murphy found a job teaching classes to able-bodied people as a certified physical trainer for Gold's Gym in Long Island, N.Y.
Murphy also just launched his own social network, Catchspark.com, geared toward motivating and inspiring people.
"A lot of people take things for granted in life, maybe, even having legs, and that's something I don't have," he said. "And I just think it gives people a different perspective, especially kids."
Watch the full story on "20/20" Friday at 10 p.m. ET