Jack was studying for the associate degree in business administration at Hang Seng School of Commerce. He was also playing in the league's third division with Tung Sing, but had neither received professional youth team training nor qualified for the Hong Kong youth squad.
"After finishing the exams in the first year of my programme in 2010, I went to Taipei with my girlfriend, where we had a foot massage," Jack says.
The masseur suspected Jack had health problems and told him to have a physical check-up when he returned to Hong Kong.
Jack took his advice and went to a public clinic for blood tests.
"The results showed my body was normal, but since I had some tiny lumps on my neck, the doctor referred me for further tests," Jack says. "I had an appointment for a hospital check-up a year later."
Jack wasn't worried about his health and soon reached a football career high.
Former football star Lee Wai-man was coaching Mutual Football Club, a second-division team hoping to be promoted to the first division in the coming season.
"Coach Lee thought I had potential and asked me to join the club," Jack says.
He proved himself at Mutual, where he became a core player. "Last June, I got an offer to enter Year Two of the global supply chain management degree course at Polytechnic University right after completing my associate degree in June," he says.
"At the same time, Mutual finished second in the league, guaranteeing it a promotion to the first division. "That was the most joyful moment of my life. What more could I ask for?"
A month later, he went for tests at Northern District Hospital.
"Doctor extracted tissue from my neck during the check-up. Two weeks later, they told me I had malignant tumours in my thyroid - that is, thyroid cancer," Jack says.
He was in no immediate danger, but was so stunned he stayed in hospital overnight.
"That news was so shocking for me," Jack says
"I didn't know what to say, and I shouted and cried in the hospital. "I felt helpless at that moment."
He phoned his father and girlfriend and announced his health condition on Facebook.
However, he kept the news for his mother, who was also unwell at the time. "My mum hurt her spine and had been in another hospital for months. I didn't want to alarm her," Jack says. When his dad told his mum the next day, she was as devastated as Jack.
Meanwhile, Mutual, now named Pontic, was facing financial difficulties. "My coach called to say the club would probably manage to keep going," he said. "But I told him it wouldn't affect me, since I had just been diagnosed with cancer," Jack says. "I felt I had wasted the efforts of coach Lee, as he'd had high hopes for me. I was so sorry."
Soon afterwards, Jack had surgery to remove his thyroid. He was left with a long, U-shaped scar on his neck and will need to take medication for the rest of his life.
One month after the surgery, he received radiation treatment to clear the remaining cancer cells.
Jack's form in football deserted him. But Lee still asked him to join the Shatin Sports Association, a second division club whose players came mostly from Mutual's team.
"They even registered me as a player in the league and always welcomed me to train," Jack says. "I had a chance to play half a match in early February, and that made me really happy."
Jack has remained determined to fight the disease. "I don't believe in fate," he says.
"I am now more concerned about my health," he says. "Before, I went to bed at 2am or 3am. Now I choose to lead a normal lifestyle and avoid putting too much pressure on myself."
Cancer cells have now spread to Jack's lungs. But he received further radiation treatment last month. "I will stay strong, since the feeling of not able to play on the pitch is worse than the pain I got from the sickness," Jack says.
"And the only way to play again is to cure my disease."