Former commando Winston Ng bounced back from a car accident in 2002 - when a broken knee left him struggling to even walk - to running marathons in just over 3 1/2 hours.
In over a week's time, the Singaporean will take on his toughest running challenge yet - a 148km relay run at Mont Blanc, on the French-Italian border.
"It is the pinnacle of ultra-trail running," said the 42-year-old, who stays at home to look after his two daughters, aged nine and seven. His 35- year-old wife is an account manager.
"To even qualify, runners need to hit a minimum number of points by running other trails. It's also expensive because of the travel costs."
When he saw that sportswear manufacturer Asics was looking for amateur runners for its Beat The Sun challenge set at Western Europe's highest peak, he jumped at the opportunity. He is one of 15 amateur athletes chosen from 8,000 applicants worldwide.
He will be in the Asia-Pacific team which also includes Asics Asia's assistant manager of education and training, Mr Andy Neo, from Singapore.
All five teams taking part - representing Asia-Pacific, Northern Europe, Southern Europe, the Americas and Africa - are made up of three amateur and three professional runners. Mr Ng is considered an amateur runner, while Mr Neo is a professional.
They aim to finish the trail, which climbs 8,370m, within 15hr, 41min and 35sec - the time between sunrise and sunset - on June 21, the day of the year with the most hours of sunlight.
Mr Ng will run a 12.5km section and the final 12km section of the relay - both of which are downhill, but which he said will be hard on his leg muscles.
Mr Neo, 35, will run two sections of 15km and 16km, both of which are steep uphill runs at a higher altitude.
Both men have had to make do with training on Singapore's flatter terrain.
Mr Ng has been clocking 60km a week and practises downhill runs at a slope near his home in Chong Pang, while Mr Neo usually jogs 3km to Mount Vernon and repeatedly runs the 30m-high hill.
Mr Ng restricts his runs to the area around his home at times when his daughters are asleep or at school. He added: "I run for my family."