When you ride fast and then rest for a bit, it causes a spike in your heart rate and helps your body deal with lactic acid. But you don't need to make it too complicated. Yorkshire is perfect because the hills work as intervals - you ride up them hard and then recover before the next one. Or you can just sprint to the next tree or lamppost.
The run's the business end of a triathlon: it's where you win or lose the race. I like to get out very hard, make other people hurt sometimes, and other times leave it to the last kilometre and really win the race there.
You shouldn't eat anything new on race days. Eat simple foods, and ones that you can easily digest.
Triathlon is a sport where the legacy is obvious. Anyone can do it; there are loads you can do. It is a massive participation sport. You can do it as a challenge, for charity or whatever. I believe it will continue to grow, and I will look forward to that happening.
I knew I wanted to be a professional triathlete, but I didn't know it was possible until I won the junior champs. My dad said I should give Cambridge a go to see if I could do both, but it was only ever a trial.
I did a term at Cambridge University studying medicine, so I could potentially have followed in Mum and Dad's footsteps and become a doctor.
I wanted to be an endurance athlete from a young age. I remember being in a careers class at school and saying I wanted to be a professional athlete and the teacher replying, 'You're not going to make it; it's not possible.'
I did my first cross country race when I was about 10 and absolutely loved it. I wasn't particularly good, so I didn't just carry on because I was good, but it just really appealed to me.
It's good to put on some lube under your wetsuit, so I tend to use a lot of baby oil on my arms and legs. It stops you chafing and helps you get your wetsuit off after the swim.
Triathletes can push themselves quite hard, and I have seen people collapse on a barrier or pass out on a bike.
I was bribed into starting swimming with the promise of sweets and by being told that you can win medals. My mum had given me a bag of medals which she had won when she was young, so the idea of winning medals was very exciting.
My first event was in Nottingham, aged 11, and the prize was a bike. I thought, 'Wow.' I had no idea what to wear. I think I did it in swimming trunks, then just put on a T-shirt and shoes for the bike part. Triathlons felt exotic. There was a technical and tactical aspect to it as well as the endurance challenge. I was hooked.
We're proud Yorkshiremen: we grew up fell running, and we still do it whenever we can. I did my first fell race when I was 11. It was a Tuesday night race called the Bunny Run, on a windswept moor above Haworth, and the prize was a chocolate egg.
Whenever we race in London, the noise of the fans gives me goosebumps.
When you train seven days a week, you need good scenery to inspire you.
Rio was always going to be on the schedule for me, whether I had won in London or not. Triathlon is one of those sports where the Olympics is always the most important and the most interesting race, and I always wanted to have a crack at Rio and defend my title.
The best thing about having your brother in the same sport as you means you can go out and train together every day, and we can push each other on. That's something many of our rivals don't have when training day in day out.
I don't know whether endurance sports attract obsessional people, or training for endurance sports makes people obsessional... it's the chicken and the egg.
I'm a Conservative. I don't believe there should be too many rules. There should be lower taxes.
The great thing about running is that you can get away to your own thoughts and get in a little bubble.
