Today - more than a decade later - Yeung divides his working life between teaching PE part-time at a secondary school and being a professional clown.
He takes the clowning part of his life very seriously; with a group of other clowns, he works as a volunteer visiting sick and underprivileged people around Hong Kong.
"Clowning isn't about doing funny things to make people laugh," says Yeung, 26.
"It's about paying attention to the audience, which requires a high level of sensitivity, honesty and respect.
"I like what I do; a clown can cause emotions and ease tension; it connects people and draws out their imagination.
"I've learned it's not the laughter that matters. Some patients are too sick to laugh or give you any response. It is my appearance that matters: it shows them that someone cares to perform for them," Yeung says.
"Seeing Cirque Du Soleil sparked a lifelong dream. I was a Form Three student and said to myself, 'I will run away and join a circus'. I knew I wanted to be a clown."
Although he chose to stay home and carry on with his school work, the dream of being a clown never left him; right after the show, he started months of training learning how to juggle. He made his debut as a clown in 2003, the year he finished the HKCEE. That Christmas, he gave his first outdoor performance in a shopping mall in Tsim Sha Tsui.
"I was playing with the kids while many people were standing and watching us," he says. "It was a special feeling: it made me happy to see them enjoying themselves and laughing happily."
After graduating from university with a degree in physical education and recreational management, he chose to teach only part-time - so that he could afford to pay his bills - while continuing with his work as a clown. "Money is not as important as doing something I love," he says. "And I want to do something good with what I love doing."
For a few years, he had been thinking of creating a character, called Caring Clown, who visits hospital patients and the underprivileged.
His dream came true in April when he received a HK$5,000 grant from Make a Difference, a Hong Kong social platform for young people, which he used to buy clown equipment.
He started making regular visits to cancer patients at Grantham Hospital, in Aberdeen, children with special needs, and low-income families in the Benjis Centre, a local charity organisation in Kowloon.
He soon realised there was a huge demand for such services, and recruited seven other professional clowns to help with the voluntary work. "What I can do by myself is limited. So I thought, 'Why not create a platform for other clowns to help?'.
"The service we offer brings meaning to the lives of those people we meet, and also to ourselves; it helps raise our personal goals and gives purpose to the clowning profession."
He has even bigger dreams for the future. One day, he hopes to work as a clown in front of children in poor countries and war zones around the world.
The idea was inspired by Hunter "Patch" Adams, an American doctor who founded the not-for-profit holistic healthcare organisation Gesundheit! Institute and its Global Outreach. The doctor's life and work - which includes promoting humanitarian clowning - inspired the film Patch Adams, starring Robin Williams.
"I want to tell people that happiness is simple - that the world is so much more beautiful when you are a happy person."