Playing in front of big crowds on the biggest courts is part of why Roger Federer is still on tour at age 33, with the 17-time Grand Slam champion saying he also gets inspiration from the accomplishments of the world's other great athletes.

Federer was chosen as a guest for the BBC's Today show by Speaker of the House of Commons in Britain, John Bercow, who was guest host. Federer told the program that once he reached the top and learned to deal with defending titles and being No. 1, he stayed driven by seeing the dominance of those in other sports.

“I realized very quickly that it's an entirely different thing winning something for the first time and then having to come back the following year and defend it,” said Federer. “Once I reached a certain level...I looked up to the great other athletes out there, like Michael Jordan, Tiger Woods, Valentino Rossi, and Michael Schumacher—people who did it so long, so many times and make you wonder, ‘How did they do that?’

“Next thing you know, it's like you're part of that in a small way, and every year that goes by you get closer to those people. They were definitely a big inspiration for me to keep working hard.”

Federer, who draws huge crowds at every event he plays, indicated that one of the reasons he keeps competing is that he is still able to play on the big stages.

"I definitely am fortunate to always be playing on Centre Court and very often prime time," said the world No. 2. "I must say—and this is honest—I don't know if I would still be playing if they would put me on Court 4 every day.

"That would be difficult for me, having played on all these wonderful courts around the world and now playing in front of a fraction of those people—that would be rough."

Now a father of four, Federer also talked about his children, saying he does not know whether they will also be tennis players or athletes themselves.

"I don't know if the kids are ever going to play tennis at a high level like that," he said.  "Honestly, I think it all depends on how things are going to be when we settle in Switzerland, and what sport they are going to take up. But I think for any kid it's important for them… to enjoy what they're doing, whatever sport that is."

Federer has spent most of the offseason in Switzerland, and played a charity match there against Stanislas Wawrinka this week. The BBC interview can be heard here.