Hi Iwan. What are you up to at the moment? Didn't you do the London marathon recently? Yeah, I did, but I actually had a bit of a bad time at London so I'm doing the Edinburgh marathon to try to make up for it [update: Iwan was ill and couldn't run in Edinburgh in the end]. I had really bad stomach cramps at about mile 16 and I had to stop. I finished, but it was just a horrible race so I decided about three days afterwards that I need to do another one. And then that's it for running this year. Well, I'll do the Great North Run and the Great South, smaller runs, but marathon-wise that's it. I'll be swimming instead! I have done triathlons before, so I'm no stranger to a wetsuit, but it will be amazing to swim in places like Windermere and Loch Lomond.
Where's your favourite place to run? At the beginning of my usual run where I live, near Southampton, I go through a place called the Royal Victoria country park. That's a nice place and it's also slightly downhill, so I like that – but then when I'm on my way home after a long run it's horrible going back into the park. So I'd say it's my favourite and my least favourite place, if that makes sense!
Do you remember your first race? Crikey, I don't remember my first ever race. I do remember long-distance, cross-country races at school – that's my fondest memory. I went to the English Schools [championship] for cross-country, in 1988 or something, years ago. I used to really like long-distance running at school. Out through the fields, round all the marshes, I used to just love digging deep and getting muddy, and I used to win as well so it felt great.
What's your greatest running achievement? I think probably the whole of the 1998 season, where I become European Champion, won the World Cup and the Commonwealth Games, all in the space of about two months. That summer of 1998, if I can have three in one, that would be it! That was my best year, then after that I had loads of injuries, unfortunately. I ran faster the year before but in terms of individual medals, that was the year that I really broke through.
When people ask you for a training tip, what do you say? I normally just say that nothing substitutes hard work and if you want to do well, in any sport, you've got to put the hard work in. It doesn't matter how talented you are, that will only get you so far – to actually achieve the next level you've got to really, really push yourself. The best training sessions I ever had were probably the ones that didn't feel so great when I was going through it, but I still did it, and that's money in the bank. It's those training sessions on the cold winter nights that count, not necessarily the really nice ones when you are away warm-weather training and everything's lovely. It's the ones where your rivals might not be training, or you're feeling rubbish; they are the ones that get you through.
Do you wear a running watch or gadget? Yeah, I used to wear a Garmin 405 Forerunner and I've also now started using a Motorola MotoActv – it's a watch that's got your GPS on it but also music as well. It's got everything, it's really decent – the only thing is it's not waterproof so you can't swim with it. So that's what I use at the moment.
Ah, so you run to music then? What do you listen to? Yeah, I do. I normally have it on shuffle. It's a mixture of stuff, which can be highly embarrassing when it's got Take That music on when I'm trying to dig deep … But I listen to anything, so whatever's on my playlist, it just goes through it. Like anyone, I like a bit of upbeat music if I'm feeling tired – I might put it on to Prodigy or some music that helps you dig deep a little bit. Because it does hurt and I do find long runs very boring, if I'm honest with you, so I need music to get through it.
Was there a song that got you hyped up when you were competing? Yeah, there was: Prodigy's Firestarter. That was the tune I used to warm up to. That was the one.
What's your post-race indulgence? The last couple of years I've actually had a pint during the London Marathon. All the crowds were so great, and there are all these lads going, "Go on, Iwan!" and waving their beers at me … This year it was a woman. She said, "Come on, Iwan!" and I stopped and said, "Can I have a bit of that?", and she said, "You're joking, right?" and everyone around her started laughing. So I nicked her pint of lager, downed half of it and carried on. Hey, it's carbs and stuff, right, it's actually quite good for you. But my actual post-race indulgence would, if anything, be a burger or a pint of lager … or Guinness! Guinness and black is my chosen drink.
What's the worst thing about running? I found that out at the London Marathon with these stomach cramps. And what that can lead to – but without getting into too much detail 'cause I've got my dinner in front of me – I nearly had a bodily malfunction this year. Yeah, it was pretty bad. It's just my body isn't used to running for those long periods of time. Obviously, being a sprinter everything was over so quick. Everyone comes past me and says: "Oh, you should be doing better than this!" I can't. I'm not designed for long distance.
What's the best thing about running then? Just the sense of achievement when you've done it. Even today, I think when I get home I'm going to try to do a long run. Even though I really don't feel like it, and the way I feel right now I just can't be bothered, I know when I get in from doing it I'll feel really good.
What do you eat on morning of a race or a long run? Normally it's quite boring, really. Just some Marmite on toast and a cup of tea and some fruit juice or something. I try not to change my routine too much.
What's the furthest distance you've ever run? 18 miles in training, but obviously the marathon, so 26.2 miles.
Do you ever run barefoot? Never tried it, no. I know people say it's good but I've not tried it.
What about the barefoot-style shoes? I've got some of those Vibram shoes but I've not worn them yet. But I quite heavily pronate, I'm quite flat-footed, so I am paranoid that if I were to run barefoot I'd just get injured. I know the studies do show that it's probably the most healthy way to run but with me, I need some protection; my arches are so rubbish that I'd just get injured.
If you had to choose who to watch, would it be Mo Farah or Usain Bolt? If I had to choose one?! How can you make me choose? I'll have to keep it British, 'cause I've known him since he was a little boy. I'll have to say Mo.
Even though you are a sprinter? Yeah, well he's out there longer, isn't he? You get more for your buck! With Usain Bolt it's all over in nine seconds.
Good point! So who is the greatest runner ever?
Usain Bolt is going to be. Yeah.
Really? You sound surprised?
Because you didn't choose him to watch over Mo. Well, I had to stay British and go for Mo! But actually, I still think Michael Johnson is up there. It was an honour to race against him for my whole career, so I'll say Michael Johnson.
• Iwan Thomas is an ambassador for the Great Swim, the UK's biggest open-water swim series. Find out more at greatswim.org