As he trudged along the Mongolian highway, he tried not to think about the blisters that were multiplying on his feet. Cars zoomed past his lone figure while the heat enveloping him soared above 40 deg C.
In those moments, when the inner voices told him to give up, Singaporean Scott Tay dug deep to remind himself of his mission - to conquer his own limitations while doing good for others.
In April, the avid traveller who had been to 28 countries over nine years, and had just completed a six-month backpacking trip in Mongolia, realised he was losing the drive for roughing it.
The 25-year-old decided to set himself a challenge to rediscover his sense of adventure.
Inspired by a story of Briton Ash Dykes, who spent 78 days walking through Mongolia in 2014, and encouraged by his girlfriend, who told him to "give it everything" he had, Mr Tay decided on a similar expedition.
He also decided to use it to raise $10,000 for the Singapore Cancer Society in memory of his grandfather, who died of lung cancer in 2006.
His journey involved walking 800km south from Ulaanbaatar, which took him through some of the planet's most extreme climates.
"I wanted something really challenging," said the founder of Beyond Expeditions, a travel group that focuses on journeys off the beaten path.
This expedition is to convey a message to cancer patients and the less fortunate, telling them that there are always people going the extra mile to walk with them during their journey.
MR SCOTT TAY, 25, founder of Beyond Expeditions, a travel group that focuses on journeys off the beaten path. He decided to link his Mongolian trip to raising $10,000 for the Singapore Cancer Society.
"This kind of expedition would not only push me beyond my limitations, but would also eventually allow me to find out the kind of person I am."
Mr Tay chose the Gobi Desert, in northern Asia and the world's fifth largest desert, for its harsh climate, and he chose July for the blistering summer heat. He decided on a trek of 800km covering about 40km a day, from July 2 to 23, for that most Singaporean of reasons. "It's the most realistic figure I could clock before my reservist on July 31," he chuckled.
But the journey, more intense than anything he had ever attempted, took its toll. On day seven, after trekking 243km, he had to stop because of massive blisters and a swollen right foot.
His recuperation in a small village, where a nurse popped about 10 blisters and treated him to prevent infection, took three days.
That was 120km lost. With the clock ticking, he decided to continue his journey by bike.
On July 23, Mr Tay completed 802.51km, slightly more than his target.
He has raised over $8,000 so far and is unfazed by any criticism of his motives - for instance, seeking publicity - for embarking on such an arduous journey.
"If I'm affected by the little things they say, it's just going to bring me down and will affect my trek - and what's the point, right?"
Mr Tay's determination and confidence surfaced often in the interview, as did his goal to raise funds for cancer survivors.
"This expedition is to convey a message to cancer patients and the less fortunate, telling them that there are always people going the extra mile to walk with them during their journey."
He is already planning the next trip: Cycling through India from south to north. He is firmly of the belief that "if you're not adventurous... you won't grow, you will stay in that same spot for the longest time where you won't evolve".