When Mr Lim Yong Jin was in then Jurong Junior College (JC) in 2016, he was made captain of the JC's taekwondo team, and represented the school regularly in competitions.
When he did not do well enough in his A-level examination in 2017 to get into a local university, he repeated his second year in JC to retake the A levels.
But in 2018, during the preliminary examinations, he was diagnosed with a rare disorder - autoimmune limbic encephalitis - which results in seizures and possible short-term memory loss.
"It started with a fever, and I was sent to the intensive care unit and hospitalised for two months," said the 20-year-old, whose father is a private-hire driver and mother, an administrative clerk. He has an older brother.
"My memory of that period is a blur, but I know I had seizures every day for a month," he said.
The Sportsman of the Year, an award his school gave him, had to pick up motor skills like walking and writing all over again.
Mr Lim has been receiving physiotherapy and occupational therapy two to three times a week over the past year to reduce his body tremors. He is also on daily medication to keep his seizures in check, and has hospital check-ups every three months.
"At the start... I couldn't stabilise myself while standing. Writing was also a challenge," he said.
By the time he returned to school in February last year, Jurong JC had merged with Pioneer JC to become Jurong Pioneer JC.
"I had to adjust to the new school campus. Most of my classmates had graduated... and people didn't know what had happened to me," said Mr Lim.
His teacher assigned classmates to be his buddies. They would stay near him as he navigated the stairways, and even bought food for him in the canteen when it was too crowded.
Mr Lim, who was given more time to complete his papers, scored Ds for chemistry, economics and mathematics, Cs for biology and General Paper, and a B for project work.
"Whenever I write, my muscles twitch, and that's the first indication that the seizures could start. Thankfully, it never happened," he said.
He may not be able to take up taekwondo again, but he has returned to school to help mentor his juniors, and hopes to become a physiotherapist.
"Over time, I've come to accept my condition and I've grown mentally stronger and more prepared for challenges."