The scars on Perry's knees are the best record of his efforts.
"Triathlon is not really a very dangerous sport," says the Form Five student from La Salle College. "It's just me sometimes being too ambitious going round a roundabout or wanting to pass other cyclists on big bends during the cycling leg of a triathlon."
Perry's mum asked him not to be so aggressive on the road because she doesn't want to see any more scars on her son's body. But she was lost for words when she heard his reply. "I told her boys need to have something special to be cool among their peers. These scars increase my uniqueness," says Perry with a smile.
His friend Hilda, also a fifth former from Heep Yunn School, does not have so many scars on her legs, but that doesn't mean she's not hard-working.
"I once cut my foot on a beach when running into the sea for the swimming part of a race. I also hurt my ankle when running up a mountain. But triathlon is a sport that I really love so I always forget the painful moments I've experienced," Hilda says.
Hilda's family are all volleyball lovers; her mum is a coach and her elder sister plays for her secondary school. "I know nothing about volleyball ... I don't want to play a sport in a standardised venue," Hilda says. "The distance of a triathlon may be fixed, but every time, the route and difficulties are different. I like the feeling that I can overcome my limitations in a race and get closer to nature."
The pair's coach, Wan Shu-wah, keeps both athletes grounded. "When I hear Wan's voice, I take a raincheck on enjoying nature and speed up," says Hilda.
Both triathletes learned to swim at the same club when they were kids.
"We realised [during a random chat] that we should have met each other years ago, although we have been training together as part of the triathlon squad for several years," says Perry.
With their hard work and determination, it's no surprise the two teenagers have excelled in their sport. They were the only Hong Kong junior representatives at the International Triathlon Union World Championship grand final in Budapest, Hungary, last September. And both did well in the 2011 Mekong River ASTC duathlon Asian Championships in Thailand last month. Hilda won two gold medals in the junior girls' triathlon and aquathon, while Perry clinched a silver in the aquathon and a bronze in the triathlon. But neither is obsessed with winning medals - it's the effort that counts, they say.
"The ITU World Championship grand final is the highest-ranked tournament in which we can compete as juniors," says Hilda. "We treat participation as a great achievement and we would like to compete with the world's top junior triathletes once again in the same competition to be held in Beijing this year.
"I really want to be like our senior [triathlete] Daniel Lee Chi-wo, who has reached Asian Games and Olympic Games standard. Wan encouraged us to work hard, and said we would have a chance to compete in the 2013 National Games if we continue improving. It will be a big step to other major championships and an eye-opener for us."