During his school days, his parents were unaware of the hardships he faced trying to lead a normal life.
It was only after 20-year-old Daniel Tan died that they were told by his friends of the tribulations he faced.
Like how the first-year undergraduate at Nanyang Technological University would walk two hours to get to his lectures from his residential hall, despite being tired and breathless because of his heart condition.
Or how, when he was at the School of the Arts (Sota), he had insisted on taking his examinations under the same time limit as the other students.
"I cannot describe how proud I am of him," Mr Tan's mother, Madam Leong Oi Leng, said of her son, who suffered from hypoplastic left heart syndrome.
The public policy and global affairs student died last week in Singapore General Hospital (SGH) due to complications of the heart and pneumonia.
He was on the way back from Kuala Lumpur on June 20 with his family when he complained of chest pains.
"He told us that his chest was really painful and he was also coughing a lot," said his father, Mr Tan Kwee Hoe, 58, a quality control inspector.
"He wanted to go to the hospital as he knew he needed help."
The family, who had gone to KL for a church event, rushed him to SGH once they arrived in Singapore.
At the hospital, they were told he needed to be intubated to help him maintain an open airway.
"Daniel needed to be put in intubation because he had low oxygen levels," said Mr Tan.
But her son initially refused the treatment, said Madam Leong, 53, an early childhood educator.
"He knew he wouldn't be able to talk once the tube was inserted, so he wanted the chance to talk to us first," she added.
She felt her son knew his time would soon come to an end.
"He told us to gather everyone around so that he could say his last goodbyes.
"We kept telling him that he would pull through, but I think he knew this time it was different," Madam Leong said.
Visiting the hospital had been a regular occurrence for the family due to Mr Tan's condition, which has affected him since birth. So they thought that this time he would recover, just as he had in previous occasions.
Madam Leong recalled how quickly events transpired on the day of her son's death.
"He informed me that he wanted to relieve himself, so I stepped out of the room to give him privacy.
"While I was waiting, the doctor came out and informed me that Daniel had no pulse and that they were trying to resuscitate him," she said.
"I was shocked. It all happened in a matter of minutes."
When he was born, doctors were pessimistic about Mr Tan's chances of living.
Yet Mr Tan, the oldest of three siblings, inspired many by overcoming the odds.
Ms Rona Tan, the school counsellor for Sota, said: "He never complained about his situation and would always ask to be treated like a normal student."
Mr Tan, who was featured in The New Paper last year for achieving excellent International Baccalaureate (IB) results despite his condition, studied visual arts at Sota.
Said Ms Tan: "He took exams under the same time conditions as the other students and even participated in sedentary activities (such as being a referee at football matches) during PE lessons as much as he could."
Dr Yap Meen Sheng, who was the vice-principal of Sota when Mr Tan studied there, spoke of his selflessness.
He said: "I remember asking him why he insisted on taking the train when his parents (had) arranged for (a) taxi. And he told me it was so he wouldn't burden his parents."
Madam Leong added: "Daniel has been an inspiration for many people and we hope that his story will continue to inspire others."
Very rare heart condition
Hypoplastic left heart syndrome is a congenital condition in which the left side chamber of the heart is significantly underdeveloped.
The left side chamber is responsible for pumping out oxygen-rich blood from the heart to the body, while the right side of the chamber pumps oxygen-poor blood from the heart to the lungs.
A patient with this condition are unable to pump sufficient oxygen-rich blood to the rest of his body due to the much smaller left side chamber.
"Hypoplastic left heart syndrome is one of the rarest types of congenital heart disease," said Dr Paul Chiam Toon Lim, a cardiologist with The Heart and Vascular Centre at Mount Elizabeth Hospital.
"There is no known cure for it and without surgery, it is generally fatal in early life. Surgery can be performed to try to correct the abnormalities and can prolong survival to the 20s or even 30s.
"However, survivors may experience chronic health problems and longer term prognosis is unknown."
This article was first published on July 03, 2015.
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