"My family isn't rich, and my mum and dad aren't 'tiger parents' who spoil their children," says Harrison, 18. "They don't buy brand-name clothes or live extravagantly."
Far from being spoiled, Harrison has always thought about people less fortunate than himself. He made his first charity donation in Primary One.
"I saw a television programme about African children, made by Unicef," he says, referring to the United Nations Children's Fund that support children around the world. "I told my parents I wanted to give the children my HK$100 lai see money, and they helped me do it."
About a decade later, when he was 15, he became a Unicef Young Envoy and started taking part in activities held by the NGO, including making a trip to Nepal to visit poor children.
"Through Unicef, I learned the meaning of children's rights," he says. "When I was a little boy, I'd just feel sorry for underprivileged children. The sympathy I had for them was rather condescending. But now I realise it's their right to be protected and educated."
On July 12, he represented Hong Kong at the United Nations Youth Assembly in New York. The conference was attended by 1,000 young delegates from around the world, including Malala Yousafzai from Pakistan. Last October, Malala was shot by the Taliban because of her determination to go to school.
Harrison says listening to Malala speak inspired him even more. "She said: 'One child, one teacher, one book and one pen can change the world'. Her speech moved me, especially knowing what has happened to her."
In his own three-minute speech, he shared his vision of a quality education for all, including Hong Kong's ethnic minorities. "They're studying in a school environment fit only for native Chinese speakers; it doesn't equip them with the skills they need to find work," he says. "Our system has led to segregation, and to them being labelled in a negative way."
The plight of ethnic minority groups is close to his heart. "It's similar to what happened to my grandfather, a Hakka who fled to Hong Kong during China's civil war," he says. "He spoke no English, the working language here 60 years ago. This inability to speak it left him jobless and left the family in poverty."
Yet his grandfather was determined to break the cycle for his children by putting all of them into school, when other parents sent their children out to work.
"He made my father learn English and watch Pearl, the English-language TV channel. His decision turned around the lives of my father and his children."
Back in Hong Kong, Harrison has begun to advance his cause of helping ethnic minorities, and has spoken at the regular Sunday City Forum held in Victoria Park.
Harrison has also created a task force with 20 young people who share his ideas. Their first mission is to become familiar with the issues by talking to ethnic minority youngsters. The goal is to persuade the government to improve the education system to cater for minorities, too.
"Having an education that prepares a young person for work and life isn't a privilege, it's a right," Harrison says.
"Our education should be fit, not only for most, but for all."
To learn more, go to www.unicef.org.hk/educationfirst