A mother-of-three and a 70-year-old pensioner from Kent are tackling the world's toughest foot race.
Mimi Anderson trained while wearing five layers of winter thermals
Mimi Anderson, from Matfield, and Jack Denness, from Rochester, are taking part in the three-day 135-mile Badwater Ultramarathon being held in California.
The gruelling Death Valley course sees runners start at 282ft below sea level and climb to over 8,000ft above ground.
Mr Denness has already completed the course 11 times in 12 attempts, while it is Mrs Anderson's first attempt.
The US race, which begins on Monday, is set in a three million acre national park where temperatures are up to 54C (130F) in the shade, and there is less than two inches of rain in a year.
It is widely regarded as the toughest ultramarathon in the world.
Mrs Anderson admits she probably has a "slightly obsessive personality".
"I think you have to to a certain extent to do what I do," she said.
Jack Denness started marathon running after he quit smoking
The distance runner only began running six years ago, but has since completed several ultramarathons, including a 140-mile trek across the Sahara Desert.
In order to train for the high temperatures she has been running near her home kitted out in five layers of winter thermals.
Pensioner Jack Denness has run the race so many times that he has been nicknamed Death Valley Jack.
However, he has said this year's race will be his last attempt.
Mr Denness took up jogging at the age of 45 when he gave up smoking, but has since run more than 150 UK marathons, including 14 London Marathons.
He runs 26 miles every Sunday, the equivalent of a full marathon, to keep in shape and has raised more than £100,000 for a host of charities.
Speaking ahead of this week's race, the school caretaker said: "I'll get across that finishing line even if I have to crawl."