Phil Cooper pounds the streets in training
He is hoping to complete 151 miles – the equivalent of five and a half marathons – in six days in the blistering Sahara desert.
His epic journey will take place in April and he hopes to raise £15,000, inspired by his mother, Margaret, who died in 2007 from ovarian cancer.
Mr Cooper, 32, hopes to raise £7,500 for the Ovarian Cancer Action and £7,500 for Loros.
He said: "It was hard when my mum died, and thought I would do something positive before I got too old.
"I've done marathons in the past and I'm in the Leicester and Nottingham marathons this year as training.
"The training is going well and the distance isn't going to be hard to prepare for, it's the heat I'm worried about."
The 800 runners will race through 151 miles of sand in 120 degree heat.
They will have to carry food, clothes, medical kit, sleeping bags and water with them as they run.
Phil, a software business manager from Rothley, is running about 40 miles a week as part of his training, but says the distance will increase significantly the closer he gets to the event.
He is hoping to use a treadmill at Loughborough University as an atmosphere control tank, where he can acclimatise to temperatures reaching 120 degrees Fahrenheit.
As well as coping with the immense heat of the desert, he will also have to contend with temperatures dropping close to freezing during the night.
Phil's wife, Kate Cooper, 25, said: "I know how much it means to him, so I'm just trying to be supportive.
"When Phil's mother died, it affected him a lot and this run is his way of doing something. I'm certain he'll do it."
Phil has signed up to an Ultra Marathon training weekend, in Chard, Somerset, in August.
Adrian Walker, senior fund-raising manager at Loros, said: "It's a phenomenal feat to raise that amount of money and it'll be well deserved.
"A lot of people would take part in a standard marathon, but to run for six days across one of the hottest places on earth is special.
"He's a brave person and is doing a wonderful thing."
Laurie Boult, Ovarian Cancer Action's head of fundraising, said: "Our commitment to improving women's chances of surviving ovarian cancer is dependent on the energy, enthusiasm and commitment shown by supporters such as Phil.
"The charity salutes his tremendous efforts in taking part in the Marathon de Sables in support of our awareness and research work."