By the age of 14, Mr Jasper Yap had already taken part in gang fights, consumed drugs, stolen motorcycles for joyrides and even robbed a taxi driver of all his cash, which was less than $100.
After he was caught for vehicle theft and robbery, he was sent to the Singapore Boys' Home for two years in 2009. He resolved to turn his wayward life around in the home.
Last year, he graduated among the top 10 students - out of a cohort of 165 - from the Aerospace Technology course at Ngee Ann Polytechnic. He was also given the honour of speaking as a valedictorian.
Mr Yap, who is currently a full-time national serviceman, said: "When I was in the Boys' Home, I discovered I could actually study when I scored my first A in my life. Before that, my report book was full of zeros and Fs. I wanted a future."
He scored As for Maths and Science in the Secondary 3 exams, which he took in the Boys' Home.
The roots of his delinquency were sown in his primary school days, when he was constantly teased for being chubby. It hurt his self-esteem.
He did not do well as a pupil at Nan Chiau Primary, scoring only 171 points for his Primary School Leaving Examination, and ended up in the Normal (Academic) stream at Pei Hwa Secondary.
A SECOND CHANCE
On my first day in poly, I teared up. I never thought I could make it. When I came out of the Boys' Home, there were people who believed I could not change. Then, all I wanted was for others to give me a second chance.
MR JASPER YAP, who discovered that he could do well in his studies while he was in the Boys' Home.
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"When I was in secondary school, I wanted a new start. I did not want to be bullied anymore, I wanted others to look up to me," said Mr Yap.
He fell in with the wrong crowd, joined a gang, picked up smoking and learnt how to fight. It was not long before one vice led to another.
He started sniffing glue - almost daily at one point - and went on to use drugs such as Ketamine and Erimin 5 to "blank out and forget the cares of the world".
And soon, he was playing truant almost every day.
It did not help that the oldest of three sons wanted to escape from all the unhappiness at home. His father had a gambling problem and owed the banks a five-figure sum.
The quarrels at home became worse after his dad lost his job as a technician and took home less pay as a cabby.
His parents are now divorced.
One night in 2009, some of his gang members decided to rob someone for some cash to buy drugs and to play computer games at a gaming centre. He went along.
"I was not thinking. I wanted to show I was fearless," he said.
The group ambushed a middle-aged taxi driver in a lift. Mr Yap used a spanner to hit the cabby, while others rained blows on the man. The attack left the taxi driver with broken ribs and he had to be hospitalised.
Before long, Mr Yap was caught by the police and sent to the Singapore Boys' Home, where youth offenders are rehabilitated. He was 14 years old.
Life in the Boys' Home jolted him.
Besides losing his freedom, he was afraid of some of the boys who were violent. But a teacher at the home encouraged him to pursue his studies and, to his astonishment, he realised he could actually do well.
"For the first time in my life, I did something right and my parents were proud of me."
He also became a Christian, which he said motivated him to change for the better.
After his discharge from the home, he went back to Pei Hwa Secondary and did his N levels at the age of 18. He threw himself into his studies, scored six points for five subjects and managed to get into the Ngee Ann Polytechnic through the Polytechnic Foundation Programme.
The programme is for Normal (Academic) students who have done well in N-level exams, and allows them to skip Secondary 5. They go on to the polytechnics to do a one-year preparatory course that covers English, mathematics and domain-specific modules such as life sciences or physics.
"On my first day in poly, I teared up. I never thought I could make it," he said. "When I came out of the Boys' Home, there were people who believed I could not change. Then, all I wanted was for others to give me a second chance."
He did well enough to win the Ngee Ann Engineering scholarship, which covered his tuition fees and gave him the chance to attend short programmes at universities overseas, such as at the Copenhagen Business School in Denmark and the Maxwell School of Citizenship and Public Affairs at Syracuse University in the United States.
While juggling his studies, he also taught himself coding and set up a Web design business, Yosei Labs, with fellow Ngee Ann Polytechnic student Terrence Goh.
Last year, Yosei Labs merged with Eezee.sg, an online marketplace where businesses can buy and sell items such as electrical and hardware supplies.
Launched in September last year, the start-up has turned in a small profit, although he declined to reveal more.
Mr Yap and his three partners hope to expand the business to countries such as Malaysia, Indonesia and Australia in the next two years.
Mr Yap, who does not take a salary as the profits go back to building the business, said: "There were many naysayers when we were trying to build our business. They said, 'Why don't you get a good salary by getting a job? Why make peanuts setting up your own firm?'"
Still, he is sticking to his entrepreneurial dreams for now.
Mr Yap said his troubled past has, in a way, helped him to face his present difficulties, such as the stresses of building a business.
He said: "Each time the tough times hit, I think I can survive. Because I have gone through worse and survived."