He was so bad-tempered he once threatened a family friend with a knife over the death of his pet fish. He was only 14 and the family friend was in his 40s.

But it was not easy growing up in a self-destructive environment. He admitted he used to vent by punching walls and glass.

As a young boy, he was frustrated when taking his PSLE listening comprehension exam as he could not hear the instructions. He then tore up his paper.

In secondary school, Mr Tan mixed with the wrong company and recalls going to parties where sex was involved.

He said: "My teenage years were quite chaotic. I did a lot of bad stuff but I don't regret them because I've learnt so much."

After he was handcuffed in Secondary 3 following a rioting incident, he changed.

His father was just returning home with dinner. He said: "My father took out the packet of chicken rice and told the officer to let me have my dinner. At the police station, I ate my rice and felt extremely depressed about disappointing my parents.

"That night, I made a personal resolution to get better."