When I decided to sell my company, I already had enough. I live simply. I don’t own a house, a car, or even a TV. The less I own, the happier I am. The lack of stuff gives me the priceless freedom to live anywhere anytime. So I didn’t need or even want the money from the sale of the company. I just wanted to make sure I had enough for a simple comfortable life. The rest should go to music education, since that’s what made such a difference in my life.

We need to have mentors. I think I've always been pretty shameless about seeking out people much smarter and much more experienced than me from the very beginning. Michael Seibel and other people. And the more successful I got, the more leaders I started seeking out, whether it was investors, or Sheryl Sandberg at Facebook, or I got the opportunity to spend time with Warren Buffett and he became a close mentor of mine.

They win the respect, the deserved trust, of the people they deal with, and there is huge pleasure in life to be obtained from getting deserved trust. And so the way to get it is to deliver what you’d want to buy if the circumstances were reversed.

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.

I have never felt the need to trash talk, and I'm not going to start now! I just quietly do my job and then quietly step into the ring to showcase what I can do. And one thing is for sure: I'm going to leave it all in the ring. I've always had such a will to win, and I always give my heart and my soul, so I don't need to change who I am.

There are days when I wake up and don't want to move, but you must show up!