What's most troubling is the open water swim. It's windy, the waves are getting in your face and the water is a bit dirty. And there's silly things like you can't touch the bottom if you swallow a mouthful of water.

I've always been a decent runner so I've never been massively unfit, but for this I've got stronger. I've got rid of a bit of podge and I'm just a bit leaner, which means that I'm just quicker at moving, I'm more agile and I recover much better as well. At the moment I feel ultra-fit and it's been an amazing change.

Also it'll be unbelievably cold in there and the thing I'm probably most worried about is my face. That sounds silly but it's very difficult, if you're in cold temperature water, to get your head under because it takes your breath away. And then your hands go numb so you try and wriggle your fingers while swimming to warm up. It's very tough.

At the end of October I started doing a bit more swimming and learning how to swim properly, because I hadn't really done it since I was at school. Then I really accelerated in December and for the whole of January's I've been doing at least one thing a day - normally a swim and a cycle, or a swim and a run, every single day.

What's most troubling is the open water swim. It's windy, the waves are getting in your face and the water is a bit dirty. And there's silly things like you can't touch the bottom if you swallow a mouthful of water.

You wouldn't run a marathon the day before you run a marathon, you need to leave some sort of surprise for your body.

The transitions will be tough because of the nature of a triathlon, you have to get changed and dry off or whatever. But this is going to be even harder because I have to do all that, then speak on the radio, do an interview with local telly, do some press and some interviews.