During his summer holidays, Seiya Obu only had a week's rest. The Form Four student from Baptist Wing Lung Secondary School competed in the Asian Junior Wushu Championships in Inner Mongolia last month and came home with a silver medal in the boys' B-grade gun (long staff).
He has been practising wushu since he was three, but he trained especially hard this past year to make up for "lost time".
Most people experience growing pains, but Osgood-Schlatter disease (OSD) takes that to a whole new level. OSD affects children and young people who play a lot of sports. It causes a painful lump just below the knee.
Seiya, 15, began suffering from OSD in 2013, and it has taken him nearly two years to recover. He hasn't fully recovered yet.
"At first, I didn't know it was OSD," says Seiya. After being beaten at the try-outs for the World Junior Wushu Championships in 2012, he was disappointed.
He decided to do more training and got help from a personal trainer. One of the exercises meant he had to bend his left leg. That's when he felt a pain in his knee. He had trouble doing it, but the trainer insisted Seiya kept trying.
"I stuck with it at the time. I went home and went to bed, and it was only when I got up again that I realised it hurt too much to even walk," he recalls.
His father did some research online and realised his symptoms matched those of OSD.
Seiya got some physical treatment at the Hong Kong Sports Institute (HKSI). He has been a member there since he was seven, when he made the Hong Kong junior team.
The treatment helped ease the pain while he was training, but there is no cure for the disease. Doctors told Seiya he simply has to wait until the bones stop growing.
Coach Lo, who has been training Seiya, also suffered from the disease as a teenager. She arranged to cut down Seiya's training and asked him not to do any exercises that involved jumping.
Seiya had a week off after he was diagnosed with OSD, and that's the only time he has asked to take a "rest".
"If I have to wait until I've stopped growing to continue my training, I'll have little chance of doing well at the sport," he says.
He carried on training at HKSI, telling himself it was mind over matter.
"I kept telling myself, 'It's not a big deal; you can deal with the pain, just carry on'," he says.
"I don't know why, but after I mentally told myself that, my knee felt less painful when I was training."
Seiya's family found a doctor in Japan who specialises in OSD treatment. This meant the half-Japanese half-Chinese boy constantly had to fly to Japan to see the doctor.
The treatment wasn't easy. "It hurt so much that I burst into tears when the doctor pressed my knee," he recalls.
But all the pain paid off. By the end of last summer, Seiya felt better and went back to regular training.
"I'm still growing so it's not completely healed, but I can jump now and coaches say I've made great progress."
Since his comeback, Seiya has been eyeing glory. He's dreamed of being No 1 in the world at wushu since he was a child. Now he is preparing for next year's World Junior Wushu Championships. "Hopefully I can make up for all the time I've missed," he says.
Earlier this year he was awarded HKSI's Elite Sport Scholarship and he decided to be a full-time athlete. This means he gets two training sessions a day instead of just one.
More training definitely adds to his already busy schedule, but he has no complaints.
"When I was at primary school, sometimes I'd get lazy. I didn't want to practise. But because of these two years, I'd never skip training," said Seiya.
"Even though I've been doing wushu for years, I still find it very fresh. No matter how great you've become at it, every day is different. If you like it, you can progress really quickly, and this leads you to new challenges."