Campbell was first attracted to taekwondo as a child after watching The Karate Kid but initially struggled at the sport.[2] He kept at it and won his first international tournament at the age of 13.[2] He qualified for the 2005 Taekwondo World Championships and in 2006 won the WTF-Oceania Championships coming back from being down 3-0 in the final.[3][4] In order to take part internationally he was funded by his parents but shortly before the 2008 Olympics did manage to get some sponsorship.[2]
Campbell qualified for the Olympics after winning the Featherweight (under 68 kg) category at the 2007 Oceania Qualification Tournament and won the Korean Open in July 2008.[2] He broke his arm seven weeks before the Olympics, but it healed in time for him to participate.[5] However he was drawn against the 2007 World Champion Sung Yu-chi in the first round,[6] and lost to him 4-0.[7]
In July 2009 Campbell and his business partner, opened a brothel[8][9] in Auckland so he could finance his training towards his aim of competing at the 2012 Olympics in London, England.[8] His 2008 Olympic campaign had cost $150,000 and Campbell hoped to raise the $300,000 that he estimated he would need for the 2012 Olympics.[10]Prostitution in registered brothels is legal in New Zealand and Campbell described what he was opening as a high class escort agency.[10] He was backed by his parents who had previously funded his Taekwondo career, with his father having taken two jobs to fund Campbell's international competition.[10] Campbell planned to take 2 years off from taekwondo in order to work full-time before returning to training in 2011; however it was reported that his choice of business might count against him in being selected for the 2012 Olympics.[11]
At the 2012 Games he was knocked out in his first fight 6-10 by Hryhorii Husarov.
