Our business everyday is to make money for people. And I take it as seriously as doctors who are trying to cure cancer, because by giving people financial freedom, we allow them to do great things in their lives - from retire to send their kids to college, to buy their first house, to fund a business that they might want to start.

The reason I've been able to keep going for so long is because of how much I love my sport. I still haven't lost that drive. I'm still as passionate about my sport today as I was when I first laced up a pair of boxing gloves. I love preparing for battle and getting into that mindset you must reach when you're putting your body through torture in training camp.

Yes, in 2018, I was awarded the Breakthrough Prize for the discovery. I was a bit dumbstruck, never expecting that kind of thing to happen. I was keen that the money should be used well and the best way to do that seemed to be to encourage a more diverse research student population from under-represented groups.

Of all the gifts that tennis has given me over the years, the greatest, without a doubt, has been the people I've met along the way: my friends, my competitors, and most of all the fans who give the sport its life.

When we started Airbnb, no one wanted to invest. I felt like a failure so many days. It was small, it wasn't growing... A sane person probably would have quit. But we kept going through obscurity, through rejection. We couldn't raise money — but over time, it started growing.

Getting rich slow isn't actually slower. It's slower in year one, but it might be faster in year seven.