It is no place for the faint-hearted, but the former Special Air Service (SAS) fighters leading Channel 4´s gruelling SAS: Who Dares Wins contest have revealed which celebrities they would like to put through their paces.
For Anthony 'Ant' Middleton, who leads the training course that sees 25 ordinary men put through the gruelling Special Forces course, it would be Lone Survivor actor Mark Wahlberg.
"He plays a good soldier," he said, "so I'd just like to see if he can put his money where his mouth is."
Former marine Matthew 'Ollie' Ollerton gave the slightly less conventional answer of fiery TV chef Gordon Ramsay.
"I'd love to channel some of that energy and some of that fire that he's got inside. He'd be my number one."
For Jason 'Foxy' Fox it would be Mad Max star Tom Hardy as he works on 2017 war movie Dunkirk, due to be released next year. Or Prince Harry.
"I'd want someone who has been through quite a lot in his time. He seems like quite a good bloke, so I'd like to test him and take him to the next level and make him feel like he's achieved even more.
"And also Prince Harry because I reckon he could hack it. He seems like a good dude."
The three former Special Forces chatted about their thoughts on the show - which begins on Monday, October 17, at 9pm on Channel 4 - as they took part in a short but sweaty work-out session at Work It gym in east London's Old Street on Tuesday.
They even said they hoped there might be a future place for women in the SAS, which has traditionally had a "boys only" policy.
According to Foxy: "It's just tradition. It's to do with that old-school mentality that front line troops going back through history has always been men.
"We've seen it change recently with women training up to be infantry soldiers, so who knows? Look forward into the future and it could be that that changes all over the armed forces and, if that's the case, then women will be on the show."
Ollie added: "At the moment we do offer a similar course through our company called Break-Point, which has a higher percentage of women come in than men." Just in case you were looking for a new gym...
They described how the aim of the show is to put contestants through brutal psychological and physical challenges in a bid to push them to their absolute limits - and then beyond.
Or, as Ant put it, to find and "exploit" their personal weaknesses and then "isolate you and rip you to shreds, basically."
While they all had their own reasons for getting signing up in the first place, and have all faced some pretty close brushes with death along the way, Ollie's story was the least expected.
"I got attacked by an 80 kilo chimpanzee at a circus when I was 10 years old. I remember staring at its face with blood in its teeth.
"It left me scarred for life and it has changed me for life - apart from giving me chimp features, according to Foxy.
"It was biting me, on top of me and beating the hell out of me and in that moment I realised it was either fight or flight and I managed to compose myself and kick the chimp off.
"I got gangrene in my arm and nearly lost my arm. It was quite a scary experience. But it set me up for my career."
That's one CV that won't get lost at the bottom of the pile!