Now I say that if you run more than 15 miles a week, it's for something other than aerobic fitness. Once you pass 15 miles, you do not see much further improvement.

We are involved in youth testing internationally. We want to try to prove without a shadow of a doubt the relationship between physical fitness and health, not just physical fitness and ability to perform.

I've had one very bad ankle injury but otherwise I've been incredibly lucky with my fitness. I've worked hard at it and I've always been fit even compared to other players. That sustains you through various parts of your career, but I am 36.

I'm healthy now. I probably wouldn't say I'm at my best fitness level and I haven't played that much lately, but I'm healthy and that's all that matters.

For years, I always thought it was hilarious that I was this fitness guru, because fitness was just a tool I utilized to help people improve their confidence. For me, it's never been about fitness. It's always been about helping to empower people.

I've published one book before, and now I'm writing a book of essays and stories about life in Tokyo. And I have one book coming out in May in Germany, about fitness.

Guided only by their feeling for symmetry, simplicity, and generality, and an indefinable sense of the fitness of things, creative mathematicians now, as in the past, are inspired by the art of mathematics rather than by any prospect of ultimate usefulness.

For a good workout, I go to At One Fitness in North Hollywood, where my trainer, Jon Allsop, puts me through it all. I like it because it's a small gym and I've known the people for a long time. Jon will have me do cross-training where I'll lift weights, jump rope, throw around a medicine ball and I never get to stop.

There are similarities between business and sport, in the pressures involved and in the fitness aspect too.

Fitness will be a major factor in the first race and I think that will play into the hands of drivers who have been racing recently, rather than people like me who haven't raced properly for a decade. I'am not one of the favourites to start with.