That's what you do all the hard work for, to play in situations that put your body through gruelling times. If you're not up to it, pull out.

Oh, I get pretty fired up on the court. I try to play with a lot of emotion, especially when I'm playing in front of a large crowd. I want to go out and do my best, and to do that, I have to play with the most energy possible.

I was lucky enough to win the Davis Cup in my first year in 1999. I won my first slam at the U.S. Open in 2001 and became world No. 1 later that year. By the age of 20, I'd done it all.

I feel like when I'm match tough and match hard and played a lot of matches I got that competitive winning spirit going and I can get on some rolls like I did last year. I won San Jose, Indian Wells and made the semifinals in Miami so it can happen for me.

I'd much rather win in three or four sets than go the distance all the time. I seem to put everyone through the wringer quite a bit.

I am two different people. What you see on the court is just natural for me. I wear my heart on my sleeve. I have always said 'C'mon' purely to fire myself up. Off the court, I am a lot shyer. I stick to my team and my family and people I trust.

I'm more in that Rafa Nadal high-energy high-octane mold out there. I wear that emotion on the court. That's how I play my best tennis. People either like that or not. And I can't change that: that's who I am on a tennis court.