Metal screws and plates hold his body together but Mr Jackson Tan Sim Siong, 56, won't miss his twice weekly run at Hougang Stadium.
The Singapore Post postman, who is married with two children, is there every Monday and Thursday evening, pounding the rubber track.
He is a runner with a cause, hoping to complete 1,000km in 20 weeks to inspire friends and residents of Hougang to donate to the elderly with dementia and children with autism. He has not set a target amount.
The "Hougang Ironman", as some residents call him, has metal plates and more than 20 screws in his arms and left leg, the result of two traffic accidents.
In 1993, he broke two bones in his left leg in an accident at a traffic light. The bones took a long time to knit and the screws were never removed.
LIVING TO HELP OTHERS
I live a simple and frugal life. I don't go on holidays. I'd rather spend my time on charity work.
POSTMAN JACKSON TAN SIM SIONG
Then, in 2005, a car rammed into the back of his motorcycle. The fall broke both his arms - a total of four bones.
"I couldn't control my tears when I was told the bones were broken," said Mr Tan in Mandarin, who began running in his 20s and has always led an active lifestyle. "Running is my life. If I don't run, I die."
It took an operation and multiple metal screws and plates to fix his arms.
Although he was supposed to be on medical leave for a year, Mr Tan was running again within two months of the operation.
Bandaging his arms carefully to minimise movement, he began jogging up to six rounds of the track, three times a week. It hurt at first but he persisted, gradually increasing the distance as the bones healed.
He has since turned his passion into a force for good by running for charity, targeting different groups of people with each self-appointed campaign.
Saddened by the struggles of his neighbours who have a son with autism, Mr Tan decided to raise funds to help children who are autistic.
"It's very hard for the parents to raise a child who is autistic. My neighbours' son doesn't talk," said Mr Tan. "People born with autism have a harder time securing jobs, so I want to help this group ."
He also hopes to help those suffering from dementia.
It is not his first self-appointed campaign. In 2014, he ran 1,020km over six months to raise money for the elderly and underprivileged children.
The next year, he ran 55 laps of the stadium track to help two individuals in need - a Malaysian man who had been burned badly, and a woman with cancer whose husband had died.
Donors include friends and acquaintances who send him their contributions. Mr Tan has raised about $1,000 for this drive, but he hopes more donations will come in.
Taxi driver Teo Kay Huat, 53, contributed $50 towards Mr Tan's campaign. "It's a small sum, but I hope that more people will come forward to support his cause and recognise his efforts," said Mr Teo, who first met Mr Tan at the Hougang Stadium four years ago.
Mr Tan also contributes his own money to the campaigns, despite earning about $700 a month as a part-time employee.
"I live a simple and frugal life. I don't go on holidays," he said, "I'd rather spend my time on charity work."
WATCH THE VIDEO
Find out what motivates Mr Jackson Tan Sim Siong to keep running http://str.sg/4YFg