Staffordshire marathon run for MS Society
Two former servicemen from Staffordshire are aiming to complete four marathons in 24 hours.
Mark Rockey and Kevin Mellor, both 39, hope to raise £2,000 for the MS Society after friend Andrew Rushton was diagnosed with the condition in 2008.
They are running four times between the The Star pub at Stone and Harecastle Tunnel on the Trent and Mersey canal.
The runners leave the pub at 17:00 BST and hope to finish more than 104 miles and 24 hours later.
Mr Rockey said he had been inspired by comedian John Bishop's attempt to run three marathons in three days.
He said: "I thought we could do that to raise money for the MS Society, not only to put into cures and research, but also to open doors for Andy and make contacts so that he has it in place when he needs the help.
"I thought we could do four marathons in four days. Then I thought, 'why stop? why not do four marathons in one day?'"
Mr Rockey, who trains with the Trentham Running club, said he and Mr Mellor had been training hard over the past five months to condition themselves for the challenge.
"I started to do the maths and saw that although it was an enormous challenge, it was physically possible," he added.
Mr Rockey said the three friends had known each other for more than 25 years and that it had been a "massive shock" when Mr Rushton was diagnosed with Multiple Sclerosis four years ago, soon after leaving the army.
"Kev and I have felt quite helpless, and although we have tried to keep his spirits up and carry on as normal, it is becoming more and more apparent that Andy is starting to struggle."
He said Mr Rushton has been "like a kid on Christmas Eve" since finding out about his friends' plans.
The two runners are going to be supported by another friend Paul Travis, 42, from Stoke who will cycle behind them with food and other supplies.