Wong was knocked unconscious while out training on a road near his home in Tung Chung last August. When he came to, he was covered in blood.
"It was my fault as I'd run into a road that was for vehicles only," the 19-year-old nursing student at the University of Hong Kong said. "I was left unconscious by the accident. When I woke up, I realised I was covered in blood."
Fortunately for Wong, he escaped with just a few bad cuts and bruises, but no broken bones. "I had to walk using a stick for about a month, but I know I was lucky I wasn't more badly hurt," he said.
Wong was definitely lucky the accident wasn't more serious, but the injury still dented his hopes of breaking the junior half-marathon record he'd been striving for.
"At the time I was really fit and ready to break the record. I thought, 'so close, yet so far'. [After the accident] I thought my chance of achieving my goal was gone."
Not put off by the accident, Wong resumed training the next month and began the hard work all over again. He was soon called up to the Hong Kong Amateur Athletic Association's distance running squad.
Before long Wong was back to his best and managed to achieve his dream not once, but twice. In November, he broke the old record of one hour, 15 minutes, 14 seconds by winning the Unicef Charity Run in 1:14.43. The following month, he broke his own record at the Zhuhai International Half Marathon in a time of 1:12.15.
Wong's started 2014 in good form, too. He finished second, just 41 seconds behind the winner, at the Mizuno Hong Kong Half Marathon Championships in Tai Po.
"I'd been dreaming of breaking the half-marathon junior record ever since I was in Form Five, but before [last year] I wasn't good enough," said Wong.
"I spent a lot of time preparing for my HKDSE exam, and reached peak fitness after it was over. But then I suffered a leg injury as a result of overtraining. That forced me to miss [a lot of] races in 2012 and the early part of last year. Then just as I'd recovered, I was hit by the van, which delayed my plans again. But finally I got there."
Wong has benefited from joining up with a new distance running squad, which has the experienced Japanese coach Shinetsu Murao acting as consultant.
The plan is to help Hong Kong's men and women distance runners qualify for the Olympic marathon events for the first time at the 2016 Olympics in Rio de Janeiro, Brazil.
Wong is the youngest member of the squad, which also includes Lai Ho-ki, his coach at the Citizen Athletic Association.
"Coach Murao has used scientific methods to really help us to improve," Wong said.
"We wear heart monitors to record our heartbeat. We've also done tests to check our lung capacity. Every two or three weeks we have a team meeting. He uses scientific theories to explain the training methods. We have trained with him for only a few months, but many teammates - including me - have already achieved personal best times."
Wong is now preparing to run in the half-marathon at the Standard Chartered Hong Kong Marathon on February 16.
His next challenge is to knock four minutes off his best time and compete at next year's Universiade in Gwangju, South Korea, a major international student sporting event.
"I'm glad I've claimed the record and have proved to people that it wasn't all talk. I could really get the job done despite the problems of last year," he said.