David Beckham's children are incredibly competitive.

The 36-year-old soccer superstar and his pop star-turned-fashion designer wife have both been successful in their careers but David says having a privileged upbringing hasn't made his sons, Brooklyn, 12, Romeo, nine, and Cruz, six, spoilt.

David - who also has a seven-month-old daughter Harper with Victoria - said: "It would be easy for our kids to sit back and not work for anything, but they're not like that. They're as competitive as Victoria and me. We're very lucky with our boys: They want to win. They want to work at something. They know their values. That's the way we've brought them up so far, and that's the way we'll continue to bring them up.

David, 36, also still has a strong work ethic and says being told he can't do something only makes him more determined.

He explained to America's Men's Health magazine: "I am a very stubborn person. I think it's helped me over my career. I'm sure it has hindered me at times as well, but not too many times. I know that if I set my mind to something, even if people are saying I can't do it, I will achieve it.

"Even at 36, I'm still running 12 miles a game. [But] I've definitely become more aware on the field. I know what my limits are, what I can achieve, and which passes I can play. I have adapted to my age."

Although he is one of the most famous men in the world, David claims he has very few friends and he prefers to spend time with his family.

He added: "I've got friends at the different teams I've played for, but family is the most important thing to me. That will always be the case. I've got my wife. I've got my four kids. I've got parents, grandparents still, and three really good friends. It's all you need. I'd rather have three really good friends than 20 good friends."