Prayer is not monologue, but dialogue; God's voice is its most essential part. Listening to God's voice is the secret of the assurance that He will listen to mine.

A lot of athletes use sports psychologists.

Everything in tennis is so neat and nice but boxing has sport down to its essence; it is very pure and I like that.

Tipping generally changes depending on where you are in the world. In Britain you don't always have to tip, but I always make sure I do. I have a lot of respect for waiters and waitresses - it can't be an easy job and they often don't get paid huge amounts, so I think it's important to reward them and let them know if they are giving great service.

In tennis, it is not the opponent you fear, it is the failure itself, knowing how near you were but just out of reach.

I used to think that losing made you more hungry and determined but after my success at the Olympics and the U.S. Open I realise that winning is the biggest motivation.

I'm a global ambassador for the World Wildlife Fund and United for Wildlife and I am also a Unicef UK ambassador. It's important to me to support charities. I never want to take my wealth for granted.