Back in 2014, no one would sit next to Mohamed Faizal Abdullah on public buses, and at 175kg, he had to board a bus via the back door due to his sheer size.

He did not dare to take the MRT because it was just too difficult for him to squeeze his frame - which included his 68 inch waist - into the trains.

It would take him 10 minutes to walk the 200m from his Hougang home to the nearest bus stop. And the journey entailed two pit stops, because he had to sit on benches to catch his breath. He would take the lift to get up to his second-storey flat.

Ironically, while he was physically large, Faizal confessed: "I felt little in spite of how big I was. I was morbidly obese.

"Even a simple movement like bending down to pick something up from the floor would make me pant."

His size made him the target of unsavoury name-calling. Schoolmates called him "Blobzilla" and "The Blob", in reference to a 1988 horror film about a creature that consumed everything in its path.

His wake-up call came in January 2014 at a funeral of a 52-year-old friend who had weighed about 120kg.

The 37-year-old recounted: "Six friends remarked to me that I would confirm 'go' (die) as well. I told them that it was really insensitive to make such comments at a funeral.

"At that point, after I said those words, they triggered me to change.

"The main motivation was not to prove anything to people who made fun of me. I honestly didn't care what others said of me. But I just didn't want to be fat anymore.

"I questioned myself, 'Why am I this big?' People keep saying that since I'm genetically fat, I'll just have to be fat."

So he embarked on a quest to lose weight. But taking baby steps alone felt like giant strides for someone who hated walking.

He found inspiration from those closest to him.

"I wanted to do it for myself and for my parents. I didn't want to be a burden to my family, should anything happen to me," said Faizal, who is of Chinese and Indian descent and lives with his 67-year-old mother and 75-year-old father.

Faizal, who used to wear 6XL pants, said: "The real baby steps were not going for my first walk, but it was the process of getting mentally ready for it.

"I didn't look good in my shirt and track pants. I looked like a plastic bag and so pudgy. But I told myself that I cannot find anymore excuses."

In January 2014, he started going for walks at Punggol Park. He called it "brisk walking" but it was hardly brisk.

He would stop to rest on every bench along his route, which could take up to 2 1/2 hours to complete.

But he kept at it, progressing by skipping every alternate bench, followed by every two benches, and so on.

In August 2014, he tried jogging and began working out at a gym in Hougang on an average of three times a week.

He also paid attention to what he ate and drank, notably weaning himself off his seven-Cokes-a-day habit. He has not drunk a drop of the soft drink since July 2014.

Those changes saw his weight down to 142kg by December 2014. A year later, he was down to 100kg.

Last March, he was 96.3kg when he became a personal trainer at True Fitness gym.

On his career change, Faizal, who used to be a manager at The Brat, a cafe selling German sausages, and also a front office staff member at Pan Pacific Serviced Suites Orchard, said: "My job has always been serving people with what they want. Now, I'm serving people with what they need."

These days, the 1.66m-tall man weighs 88kg. His body boasts a 32 inch waistline and rippling muscles. His body fat mass is 16.7kg.

Besides working out at the gym at Djitsun Mall in Ang Mo Kio five times a week, he goes for a 30-minute outdoor run once a week, starting from Buangkok Green at 4.30am to Punggol Park and back.

He will be running in the 5km fun run at The Straits Times Run on July 16.

His transformation has surprised family and friends. When he went to the airport to welcome a relative from Malaysia two weeks ago, she was startled to see the new Faizal.

He said: "She paused to look at me and then exclaimed, 'Which doctor did you go to to get rid of all the fat?'" But he did not go to any doctor or surgeon, just to the gym.

Now, he hopes to use his life-changing experience to inspire others. He said: "Not many people will undergo this and survive. It takes a lot of perseverance, determination and courage.

"Now I don't feel so little anymore and I don't belittle myself. Now that I've shrunk, I feel bigger."

•Registration for the ST Run has been extended till Wednesday. Sign up at straitstimesrun.com

Correction note: In a previous version of this story, Mr Mohamed Faizal Abdullah's waistline was incorrectly stated. We are sorry for the error.