Two days ago, Manhunt Singapore 2014 (senior category) finalist Andrew Ang's heart swelled with joy when his eight-year-old son passed him his car keys.
This may seem run-of-the-mill to most parents, but for Mr Ang, it was a clear sign that his child Alex wanted to communicate with him.
Six years ago, the boy was diagnosed with severe autism.
Autism is a neurodevelopmental disorder characterised by impaired social interaction, verbal and non-verbal communication, and by restricted and repetitive behaviour.
Since then, Mr Ang, a 41-year-old businessman, has been worrying for his son.
He hopes his son, the middle child of his three children, can one day lead an independent life.
His oldest child, a daughter, 10, has had open heart surgery for congenital heart disease, which is a problem with the heart's structure and function that is present at birth.
Mr Ang, who is 1.73m tall and weighs 65kg, said he joined Manhunt this year to be an inspiration to his children.
His message to them: No matter how tough it gets, don't ever give up.
He told The New Paper: "When Alex was diagnosed, it was very difficult for us. We had no idea what was going on so we had to seek help.
"The one-to-one therapy, which has cost us $4,000 every month for the last six years, has helped a lot."
Mr Ang recalled that two days ago, he had left his house only to realise he had forgotten his car keys.
So he went back to get them and Alex, who was there when he opened the door, passed the keys to him.
Said Mr Ang: "I was stunned. I didn't know that he could communicate with me. To other parents, this is such a simple thing. But to me, this means he's actually seeing some light and knows what's going on.
"I hope my son can take of himself when I'm gone.