Being a single father is not easy. Being a single father with an HIV-infected child is even harder.
But when the father is unemployed and has to travel back and forth between the mainland and Hong Kong every three months carrying up to 20 bottles of medicine - while fighting off accusations of being a smuggler - the challenges seem almost insurmountable.
That was the situation faced by Mr Chan, 55, after his Myanmese wife died of Aids when their son was a year old. But he persevered.
"I had never thought of giving up," said the Hongkonger, who does not want his full name published. "That would have been impossible. I would only think of ways to face each day."
Chan has been put forward as an example to other parents by the Society for Aids Care, which has been helping him for more than a decade.
The society's chief executive, Alice Chan Lai-hing, said the pair's case had touched her a lot.
"There are some irresponsible parents who just abandon their children and let the Hong Kong government take care of them. Mr Chan is a strong man, a very great dad," she said.
Chan was working on the mainland when his wife died in Hong Kong in 1998, two weeks after being diagnosed with Aids. Doctors believed she contracted the disease through a blood transfusion while undergoing surgery in Thailand.
A relative took care of the boy at first.
But when the boy was diagnosed as HIV-positive at the age of two, Chan sensed the relative did not want to continue. After completing initial treatment in Hong Kong, Chan took his son to the mainland city where he worked in the furniture design industry.
He would not give the location, except to say that it was a two-hour flight or a 20-hour train journey from Hong Kong.
He worked for nine hours a day, leaving his son with a nanny, and spent the rest of the time taking care of the boy.
The most difficult part was giving him his medicine.
"It upset me a lot because it was so agonising for him," Chan said. "The medicine was bitter and irritating. He used to cry and sometimes vomit after taking it." He said he knew how bad it tasted because he tried it himself.
Things got more difficult when he lost his job, began working part-time to make ends meet and was unable to afford a nanny.
Even more difficult were the three-monthly trips to Hong Kong for treatment and medicine. No longer able to afford a flight, they travelled to Shenzhen by train and booked in at a guest house before crossing the border for the Hong Kong hospital visit.
They settled back in Hong Kong three years ago for the sake of his son's education.
The boy, being a Hongkonger, would not have been able to take the college entrance examination on the mainland.
Explaining why he never gave up, Chan said: "I would tell myself that there might be new medications to cure him in the future or that he would remain stable by taking his medicine."
His biggest hope for his son, now 17, is that he will stay healthy and independent.
"He has grown up and I'm growing old. I can't always take care of him," he said.