At a time when most polytechnic students went straight to work after graduating, she decided to buck the trend.
She went on to get an honours degree in virology and immunology at the Queensland University of Technology in Australia. Now, after 20 years and a post-doctoral stint, Associate Professor Lok Shee-Mei is part of the emerging infectious diseases programme at Duke-NUS Medical School.
Even as a student at Bedok Town Secondary School, she knew she was interested in science.
"But the traditional way of doing things didn't interest me because... I couldn't see the application," said Prof Lok, now 42. "I thought I wouldn't do well in a JC setting as it was going to be the same."
Instead, she signed up for a biotechnology course at Ngee Ann Polytechnic, from which she graduated in 1993. She called it "one of the best decisions I ever made".
In the early 2000s, she started working on a doctoral degree, and got married. Then, her research proved frustrating because she could not get certain protein crystals to form.
"Nothing was working out, and I thought - I need to do something with my life. So I decided to have a baby," she said, laughing.
She knew she wanted to do postdoctoral research, and the best place for that was in the United States. She went there in 2004, but her husband and young daughter stayed behind.
"I earned so little, and I couldn't support my family, so they had to stay here," she recalled. "We were apart for four years... The thing that gave me the strength to continue was that I felt I was learning something every day."
She later returned to Singapore and had a son, who turns four this year. Whether her children follow in her footsteps, however, is up to them.
"I strongly believe you should do what you like," she said. "Don't let your parents tell you no."