Mark Goh is relieved, having just finished his final exams as a first-year student at Duke-NUS Medical School.
"It's been tough," he says of his "freshman" year at Singapore's first American-style graduate entry medical school.
"All my classmates have degrees in different disciplines but most also have a background in biology. I don't so I have to work harder. I didn't know how tough it was until I got here," says the 26-year-old physics graduate from Nanyang Technological University (NTU).
Tough or not, he is hell-bent on making it.
That determination is fuelled by a longing to work as a specialist in nephrology, a branch of medical science that deals with diseases of the kidneys.
Mr Goh, you see, was plagued by kidney problems throughout his adolescence until he had a transplant with a kidney donated by his mother when he was 18.
By going to medical school, he hopes to kill several birds with one stone. He wants to continue the good work of doctors who helped him when he was ill.
He wants to give hope to children with chronic illnesses and show them, and their parents too, that they can have a bright future ahead of them.
Finally, he hopes to raise awareness and open the conversation on organ transplant.
Mild-mannered and soft-spoken, Mr Goh is the eldest of three children. His father runs a headhunting business; his mother is a housewife.
Life was comfortable and uneventful until he was diagnosed with focal segmental glomerulosclerosis (FSGS) when he was 12. It is a rare disease where scar tissue grows on the kidneys which filter waste from the blood.
He found out about his condition by accident, when he feigned a stomach ache one day. "I didn't feel like going to school because I didn't like Chinese class," says the former student of St Stephen's and St Joseph's Institution.
His mother took him to a doctor who ordered a urine dipstick test and found protein in his urine, a sign of kidney disease.
Further tests confirmed he had FSGS.
"From Secondary 1, I started taking a lot of medication, especially steroids. I developed Cushing Syndrome," he says, referring to the disorder caused by high levels of cortisol in the body. "I had a moon face, I was puffy and felt unfit," adds Mr Goh, whose parents were primed for the gradual deterioration of their son's kidneys.
He was regularly subjected to blood tests, biopsies and haemoglobin injections to his stomach.
Although he dutifully endured the treatments, many of which were painful, he admits to feeling resentful. "It's not like having the cough or flu when you get fine after being given medication. I was going to the doctor's every month and I didn't get well," he says.
Professor Yap Hui Kim, head and senior consultant of the division of paediatric nephrology at the National University Hospital (NUH), has been treating Mr Goh since he was 12.
She says: "The treatments were very difficult for anyone to go through, let alone a child. But he was a very special patient; for him, it had never been a no. It helped that he has supportive parents."
At the end of his first year at Catholic Junior College, Mr Goh started peritoneal dialysis. The procedure involves introducing a sterile liquid through a catheter surgically placed in his peritoneal cavity to clean the blood and remove toxins and extra fluids.
"It had to be done 10 hours every day; I had to stay in my room for 10 hours every night," says Mr Goh, who was on dialysis for two years.
In 2010, his mother decided to donate one of her kidneys as a transplant was the best option for his condition.
"I really didn't want to do a transplant because I didn't want to put my mum at risk," he says, referring to research which puts the risk of dying from donating a kidney at one person in 3,000. "But she really wanted to. We decided to go ahead after praying. I owe my life to my mum."
The days leading up to the transplant on Dec 22, 2010 were anxious ones. "A part of me was prepared that I might die on the operating table and might not see my friends again. So I met many of them."
Fortunately, the operation went smoothly for both mother and son.
"I was very lucky. There were no complications. One of my friends died one week after his transplant," says Mr Goh, who took five months to recuperate.
In 2011, he started his degree in physics at NTU.
Asked why he did not gun for medical school earlier, he says: "When you have a chronic illness, you really don't know what's in store. When I was studying for the A levels, there were times when I asked myself what the point of studying was. I didn't even know what would happen to me one year down the road."
The kidney transplant gave him a second shot at life. He started engaging in activities which were off limits when he was sick.
One was running. He took it so seriously that he even earned a berth in the Singapore contingent at the World Transplant Games (WTG) in Durban, South Africa, in 2013.
Then 21, he was the youngest of the 13 Singapore transplant athletes that year, and took part in three events: 100m and 200m races, and badminton. Last year, he again represented Singapore at the 2017 WTG in Malaga, Spain, taking part in the 400m event.
Getting well also spurred him to help the community of young kidney patients at NUH's division of paediatric nephrology, dialysis and renal transplantation, which Prof Yap heads.
He has, he says, made many friends there. "NUH took really good care of its patients; we became really good friends. It made going to the hospital less of a chore, and more like a meet-up," he says.
One of the highlights for Mr Goh and his young friends was an annual camp for young patients with kidney and other chronic illnesses, started by Prof Yap in 2000.
The idea behind the event is to give these children experiences - including teamwork-building activities and outdoor games - which they could not have because of their conditions.
Prof Yap says: "The main thing is to get the children out of the house and into the world, and to get their parents to let go."
The three-day camps, attended each year by 60 young patients, are fully equipped with dialysis machines and boast a team of medical volunteers to take care of any medical emergencies.
She was impressed when Mr Goh stepped up and offered to become the first patient to organise the camp in 2013.
His reason for doing so is simple.
He says: "The people at NUH had taken care of me so well. I'm in a position where I have these experiences which some of these kids don't have.
"I wanted to set an example for the younger ones. What's important is that they have people they can look up to. By doing a good job with the camp, others hopefully would also be encouraged to step up," says Mr Goh, who also rallied several young transplant patients to train and take part in the WTG last year.
The lengths he goes to to pay it forward have led Prof Yap to describe him as "a very special patient", one who even approached her to work on dialysis research after he graduated.
"He's an important role model not just for kids but for their parents. When they see him, they won't think it's the end of the world.
"He's always ready to face any challenge, even getting into medical school with no biology (background) which is a big deal,' she says of her patient who had to clear a tough entrance test to get into Duke-NUS.
Although the going is tough, Mr Goh feels he is where he belongs.
"I had a corporate job but I felt I was just making money for other people," says Mr Goh, who worked for several months as a data analyst in a company specialising in diagnostic imaging.
"But when I become a doctor, I will be helping people directly."