It appears nothing can stop teen triathlete Ben Marshall-Lee.
Four years ago, the sporty Christchurch boy was diagnosed with a rare bone condition that sidelined him for 12 months.
"I was in Year 7 and doing quite a lot of sport when I started getting pain behind the knee," he says.
An MRI scan showed Marshall-Lee was suffering from osteochondritis dissecans, a disorder where blood deprivation to the area leads to cracks in the bone and cartilage. Surgery was an option but Marshall-Lee chose to let his knee heal naturally.
"To be unable to do anything for a year was really difficult. I wasn't allowed to break out of a walk ... all I could do was some swimming and a little bit of cycling."