As a tennis player, or any professional athlete, our career has a shelf life. I don't want to waste any opportunities, I don't want to look back on it when I'm 45 and think I could have done a lot more.

I didn't know I could even be a professional tennis player, honestly. All this is actually very, very unexpected.

A lot of times when I'm confident and relaxed on the court, I'm going to be a pretty tough out. But when I'm not so confident and not so relaxed, I tense up and my balls fall short and everything. It just sort of unravels.

In the past, I've played where I only just rely on my serve.

Hillary Clinton is one of the most compelling figures in the world today... and Carl Bernstein's stunning portrait shows us, for the first time, the true trajectory of her life and career.

In 1975, I quit my tenure, and we moved from Ann Arbor to New Hampshire. It was daunting to pay for groceries and the mortgage by freelance writing - but it worked, and I loved doing it.

I've had ups and downs in my career, and if you look at it as a bookmaker, the odds of me becoming a world champion were never in my favour, but I never stopped believing in myself and never stopped trying.

Like so many others, my military career was anchored by a calling to give back to a country that had given me so much.