Well, when I walk behind short people I feel like I'm going to fall over because I start taking these little steps, and I can't take little steps.

For years I felt that I didn't have enough stamina and then, four years ago, I felt like I was not getting enough air but I was diagnosed with exercise-induced asthma. The medicine for asthma never worked.

I have to say accounting almost killed me.

Serena and I have done some great career planning, and we're playing really at the peak of our tennis right now. I think tennis has been a sport where people play this insane schedule from 14 years old, so of course at 26, it's over. We've really paced ourselves.

There were a lot of people shouting out. I know it's not proper tennis etiquette, but this is the first time I've ever played here that the crowd has been behind me like that. Today I felt American, you know, for the first time at the U.S. Open. So I've waited my whole career to have this moment and here it is. ... It was great. It was awesome. It was like winning gold.

So what if you fail? At least you'll know what not to do when you try again.

I think business is the same as tennis. You have to have the love, that helps, or else it's just too much pressure to be able to keep up with.