Celebrity SAS: Who Dares Wins returns to Channel 4 on Sunday with comedians Tez Ilyas, 40, and Shazia Mirza, 45, among those taking on the gruelling special forces training. Here they talk about their involvement in the show. 

Why did you say yes to this show?

I was asked, and it’s always very nice to be asked to do things, especially TV things. And also,I just thought what an amazing experience it would be, a money-can’t-buy experience. 

I feel like with my stand-up, I travel around and after a while it starts blurring into one. Going to towns and cities and performing and then leaving without properly exploring a place. So wouldn't it be nice to just be in a place for a couple of weeks, if you last that long!

 I'm not SAS material, so the fact that I got to do some SAS training and exercises was very, very exciting.

What were you hoping to get out of the experience?

I'm not going to sit here and be like, "I was hoping that I'd win", because I didn’t expect to win. I was pretty sure that I wasn't going to make it to the end. I was hoping just to experience it, see how much I can take mentally as well as physically, see how much of my own personal boundaries I could push, how much of my comfort zone I can be out of and still be okay and survive and be mentally intact. And I think it did that. It really stretched me, parts of it, and then part of it was just really, really fun. 

Did you do any preparation for it?

I did the best I could in the timeframe that I had because I had five weeks notice at best. 

I'm not an athlete like some of the guys on it. I can't just go into training camp mode, you know, I'm a civilian. I'm a normal guy. So I did the best I could. I hit the gym as much as I could, but I was probably starting from quite a low bar, so getting to semi-normal is probably all I could have done in the five weeks that I had.

 I probably didn't have enough time to really push myself and get myself into the shape that I would have probably wanted to be in or needed to be in. 

What was it like filming in New Zealand?

Well, as a massive Lord of the Rings fan, it was amazing. Beautiful.

Where we were staying, the airport is just on the other side of these mountains, so as you fly over to land you're really low.  We were skimming over these mountains and it was just breathtaking, the scenery around it. 

It was cold, obviously, sleeping in those bunks in what was possibly amongst the coldest I've ever been in my life. It was so cold I couldn't sleep. I was too scared to take my sleeping bag out because I was so scared that we'd suddenly be woken up at 6am with ten minutes notice to be completely ready and out the door ready to go on a mission or whatever. So I slept with a blanket.

Did you form any close bonds with the other recruits?

It was really nice because a lot of them come from different worlds to me, you know, athletes and reality TV stars. A lot of them knew each other, they were from a similar world, similar parties, similar social events. Whereas I felt like I was slightly removed from that. Me and maybe Shazia and Lani [Daniels, the boxer] were slightly removed because we weren't in the same social circles as those guys. 

But I got on with everyone, I really liked Pete [Wicks, from Towie and Strictly Come Dancing] and even though I knew Shazia from the comedy circuit, I got to know her better, which was really nice.

Were there any arguments or did you think you operated well as a team?

I didn't really notice any sort of tensions or arguments, no one was mega frustrated with anyone. I think Ovie [Soko, basketball player] was a bit less patient with some stuff than possibly other people. But I think that was because he's a real go getter, he was really good at everything as well.

What did you learn from the DS [directing staff]?

They were a mixed bag. Rudy and Chris were really nice. It felt like they treated us like people. Billy was slightly more detached, but it felt like he was more fair. 

But I did learn stuff from them, like their discipline and the fact that they've been through this for real so they really know what they're talking about. The harsh treatment is probably nowhere near as harsh as they probably suffered in the real world. That was quite inspiring in a way, like, wow you really went through this.

What would you say was the hardest part of the course.

Definitely the physical challenges because that was probably my weakness. I wasn't as physically fit as some of the others there because they were athletes. And also reality TV stars, you know, part of their job is to look good and part of looking good is being in the gym a lot. So they were very, very fit and active. Being in shape is good, but it's less important in my career. So my fitness was definitely one of the hardest things to overcome.

Would you say the physical side is harder than the mental side of the course?

Yeah, I think so. But then I don’t have issues with things like heights, so I didn’t have to overcome that. 

I guess the mental challenge for me was when they're shouting at me and I felt like I was being being singled out a little bit, but you just have to bite your tongue a bit  because if you don’t, you might get everyone else into trouble. That'll be a smart way of punishing you, punish everyone else and then you feel super guilty about it. So biting your tongue was tough, especially as a comic, you're always used to firing something back.

What was the first thing you did or ate when you left camp?

Oh, there was an amazing burger at the resort we got to stay in. So I got a really nice cheeseburger, and it was halal as well. I’d had it a couple of times before we actually started the course because I thought at that stage what harm could it do? So I had another one when I got out.

Did the show live up to your expectations?

Definitely. I’d even say it surpassed them. It was harder and more fun than I could have possibly imagined. It was uncomfortable. It was awful. It was brilliant 

Did you learn anything about yourself?

Yeah, aside from the fact that I'm physically not a specimen, it’s made me even more in awe of watching Olympic athletes, and not even Olympic athletes, athletes in general, we are the same species but what they can do with their bodies physically, I'm like, wow.

But also I now know I have some level of resilience. There are comfort zones that I go out of and I'm able to cope with that. That was nice. Maybe I do need to bring a bit more of the army discipline into my life.

Would you do it again if you had the chance?

Yeah, but I feel like I'd want slightly longer notice so I could get into better physical shape to give it a really, really good go!

Why did you say yes to this show?

Well, I didn't, actually. They asked me three times and I said no! I had friends that had done it before, like Zoe Lyons, and they told me not to do it, and so I just kept saying no. And they kept asking. And I asked why and they said, ‘because we saw you on The Island with Bear Grylls and you were amazing on that and we think you'd be great on here.’ But I watched SAS and it was horrific!

What were you hoping to get out of the experience?

Well, I didn't realise how unfit I was. I thought that I was very fit because I do swim every day. I swim in cold water. I run. I thought I was fit, actually, I'm not. 

What I thought I would get out of it is I know that I'm a strong person mentally, because I've done these kind of things before, like The Island with Bear Grylls. I survived that for a whole month without any food. I did all the fishing and it was a lot longer than this. I just thought, What can go badly wrong in eight days?’ So I wanted to see how long I’d last.

Did you do any preparation for the course?

Yeah, I did. I ran with a weighted vest, a 32 kg weighted vest every day. I used to run in north London. Then I took the vest with me to New Zealand, and I also ran with the weighted vest on for a week before we started. I was also swimming in cold water, which is what I normally do. And I was going to the gym. I was doing weights. 

So I did prepare for it as much as I can. I mean, they didn't give us much notice to say that we were going to be on the show. It was really a matter of weeks, but in that time I did prepare for it.

Did you speak to Zoe?

I did. I spoke to her quite a lot. I know her very well from comedy, anyway, and she said that she got trench foot and it was awful and they were in Thailand and it was horrific. She said it was going to be mind over matter at a certain point.

What did you think about being in New Zealand?

When they said they were going to New Zealand, I thought, "You know what? I've never been to New Zealand", thinking that I was going to see the sights. Thinking it's going to be like Lord of the Rings! 

New Zealand was amazing, the scenery was incredible, it was breathtaking, and it was a really amazing environment, but it was actually as horrific as I thought it was going to be. 

It was more Game of Thrones than Lord of the Rings, it was awful!

I do cold swims anyway, but New Zealand was freezing! And it was worse because every time we did something wrong, they wanted us to go into the ice bath head first. You think you might have got used to it after a while, but you don't because you get dry and you get warm, and then you see them taking you near water or you see them taking you near ice, and you’re like, "oh, not again!"

Did you bond with the other recruits?

Well, it was weird because every time we woke up, somebody was missing. Somebody had gone. And we're like, "Oh, where's Rachel [Johnson, journalist and sister of the former PM]? Where's Pete? Where's Chris [Robshaw, former rugby player]?" Because once they take you out, you can never go in and say goodbye, you know, that's it. Once they've left, they've left. 

I have to say the girls were fantastic. The way we really stuck together, truly, me, Rachel Johnson, [TV presenter] Cherry Healey, [Love Islander] Georgia Harrison, and Bianca [Gascoigne, reality TV star]. 

Maybe on paper we will not get on. We're so different. But the girls really stuck together and really supported each other. Ovie was so nice to me. I mean, he was so supportive and helpful and kind and just so encouraging to me, which helped me, I think, stay in as long as I did. He was really just a great support and a really nice guy.

Did you learn anything from the DS?

I learned a lot from them. They fought in Afghanistan, in Bosnia, you know, in these real, proper, dangerous situations. I learned a lot from each of them about keeping calm, about using your brain, not reacting in the moment, but just to thinking things through. 

They taught me a lot about resilience and never giving up, really, was like, no matter how tired you get, no matter how down you get, just never, ever, ever give up. And that tenacity and that keeping going when all you want to do is give up. 

He taught us a lot about survival, really, which is what this is about. It's about survival, about keeping going, why you've got to keep going, and how when you think you've got nothing left to give, you always have a little bit more in the tank.

What was the hardest part of the course?

I think it’s mind over matter. Yes, you've got to be physically fit to a point, but there comes a point where it doesn't matter whether you're physically fit, because it is mind over matter and that you are stronger than you think. The mind is way stronger than the body. When the body gives up, the mind can keep going and can really propel you forward.

So was it more a mental challenge than a physical one?

I'm good mentally, for me, it was physically, I felt that I was not that fit. I could have done more weights. And since I came out of there, I've been doing weights. I’ve been beasting the gym SAS style!

Did the course live up to expectations?

It was worse than what I expected. It was worse than what I'd seen because they can only show so much on TV. It was actually horrific. 

But, you know, when I think about the women that I was in there with, like Rachel Johnson and people like that, they were fantastic. For a 58-year-old woman she outlasted a lot of the young people. And I think from what I saw, women are mentally much stronger than men.

Did you learn anything about yourself during the course?

I learned that if I can do this, I can probably do anything. I say I fear this and I fear that, but if I had to do it, I'd do it. I'm scared of heights. I'm scared of the freezing cold. I'm scared of going really deep under water without an oxygen tank. I did everything. I did them all. I never, ever backed out of a task. I failed at tasks, but I never backed out of a task. That's good.

So would you do it again?

No, there's no need! I know Pete did it twice, but there's no need to keep doing this. If you do it once and you do it properly and you give it everything and you learn something from it, and you feel you did the best you could do, then there's no need for you to do that again.

• Celebrity SAS: Who Dares Wins is on Channel 4 on Sundays and Mondays at 9pm, from September 22. As part of the challenge they had to run down a dam. Here's Tez doing it:

And here's Shazia:

And here is the opening sequence: