A Singapore team of five men is taking part in the Gobi March, one of the world's most punishing foot races.
It is a seven-day, six-stage ultramarathon that takes place in the Gobi Desert in Xinjiang, China, from May 31 to June 6. Participants carry everything they need for a week in their backpacks.
Teams complete 40km a day for the first four days, with time allocated for rest between each day.
The next 80km-leg is conducted on the fifth and sixth day, before a 10km push to the finish line on the last day.
The race is part of the 4Deserts series of races organised by RacingThePlanet, which Time magazine described as the "ultimate test of human endurance".
The group hopes to raise $50,000 for the charity Seeing is Believing, which works to eliminate avoidable blindness globally.
Mr Ken Wee, 41, said: "It's all about living life to the fullest. Through this, we hope to give the gift of sight to others to help them live life fully as well."
The team is made up of Singaporeans Mr Wee, Mr Alvin Tan, 41, Mr Lawrence Loh, 41, and British nationals Mr Eden Britt, 42, and Mr Lee Slater, 43.
Most people expect deserts to be continuously hot and sandy but Mr Wee, who has participated in another desert race, said this is not always the case.
The bank manager, who ran in the Sahara Race three years ago, said: "We might experience all four seasons in a single day.
"At night, temperatures can go to zero degrees, and in the day, it might reach 40 degrees."
And as for the terrain, it's a far cry from being able to wiggle your toes in the sand.
Mr Loh said: "It's not all sand. We'll be wading through knee-deep rivers, climbing rocky mountain slopes, and racing through grassy plains as well."
The race is not just about speed, but about survival.
There are small pink flags planted throughout the course to guide runners, but these can easily be hidden under a mound of sand in the event of strong winds.
If that happens, they need to rely on their sense of direction to gauge if they're heading in the right direction.
Mr Wee, Mr Tan, and Mr Slater said their military backgrounds would help them in the race.
Mr Slater, who was in the British Royal Marines, told The New Paper: "During my days in the British army, I had to carry loads two to three times the weight of the supplies I'm bringing for the race.
"But in terms of the distance, I never covered anything of this distance over such a short period of time."
Mr Loh and Mr Britt, who do not have military backgrounds, have made up for it by training hard on their own by going to the gym and running regularly.
Mr Britt, who was a classical musician playing the trumpet before joining a bank, has run marathons.
He said: "I don't think it's ever possible to be physically fit enough to take on this race comfortably. After the fourth or fifth day, it's all about mental strength."
For him, the hardest part of the race is in the last few kilometres before the end of a stage because that's when he would feel most like giving up.
To donate, go to www.justgiving.com/gobimarch2015-scgrouphr
This article was first published on May 18, 2015.
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