Watch Fiona Marley Paterson's video report
A man was brought back to life after being found "clinically dead" and leaving "blood trails" in the snow on a run in the Lake District.
Tommy Price from Huddersfield was running on Halls Fell Ridge on Blencathra with his friend Max Saleh in January, when he became unwell with hypothermia.
He is one of only a handful of people specialist treatment has worked for.
Five months on, the 26-year-old now plans to run London Marathon to raise money for Keswick Mountain Rescue team after they helped save his life.
Tommy said: "Going up Blencathra I started dropping to my knees and Max just had to keep picking me up saying, 'we're going to die if we don't move'.
"We were in complete cloud cover; there was high winds; snow and it was really, really cold."
"I couldn't really walk. I was like drunk, so that was getting severe hypothermia and he had to get me down the ridge.
"I was sliding down on my bum, ripping all my shorts open, leaving blood trails in the snow. I was crying to Max saying I'm going to die up here.
"Obviously Max was very emotional seeing his best mate leaving blood trails in the snow and thinking he was going to die."
Tommy was helped into a survival bag by his friend Max, before he went to find help.
Emergency services from the Keswick Mountain Rescue team were deployed with warm clothes and snacks to deal with what was expected to be a hypoglycaemic (low blood sugar) and cold fell runner.
Yet when they arrived at the scene, Tommy's bivvy bag was empty and he was nowhere in sight.
The team eventually found Tommy further up the trail but he was lifeless.
According to the medical guidelines that Keswick Mountain Rescue currently follow, a casualty is not considered dead until they are 'warm and dead'.
This means they must be treated in the same way they would be if they were alive.
Tommy was given CPR and shocked with a defibrillator but it had no effect.
The fell-runner from Huddersfield was airlifted to the RVI Hospital in Newcastle where his temperature was just 18.8 degrees.
This is one of the lowest body temperatures someone has survived from.
Dr John Ferris from the Keswick Moutain Rescue Team said: "We recognise that people who are this cold can actually be resurrected and brought back to life.
"Essentially he's in a state of suspended animation really, where he's sort of between life and death.
"We're holding him in that state but the chance of success here was actually pretty small."
At the RVI a specialist team and extracorporeal membrane oxygenation (ECMO) machine arrived from Newcastle's Freeman Hospital.
The machine took blood from Tommy, warmed and oxygenated it before circulating the blood back into the body.
This meant his blood was re-warmed gradually.
Five tense days later, Tommy woke up wondering what had happened and asking for a can of pop.
"It's lucky that I've just got nerve damage in my hands and feet," said Tommy. "I'm just so lucky to be alive and if weren't for the Keswick Mountain Rescue I wouldn't be here, and obviously Max my best friend, I can't thank him enough for running down."
Keswick Mountain Rescue are urging people who utilise the fells to ensure they have spare clothing and a survival bag when going into the hills as it could mean the difference between life and death.
Listen to ITV News' What You Need To Know podcast: