Growing up, surfing and rugby were two of the major sports in Durban, but Lessing resisted the pressure to make the change to these activities. He trained an average of 3 hours a day in his areas of interest: sailing, swimming, track, cross-country and duathlon. He developed an interest in hiking and hiked in the Drakensberg Mountain range. His swim coach, David McCarney, encouraged Lessing to try a family oriented race he organised at Kloof High School. In 1988, Lessing was the South African triathlon champion. He was selected to represent South Africa in a biathlon but suffered a broken leg in an accident during a local triathlon.