Will Smith has revealed the secret of his 10-year marriage: divorce isn't an option.

The The 'I Am Legend' star explained his approach to wedded life to US talkshow host Ellen DeGeneres.

On Monday's episode of her show, DeGeneres reminded viewers that Smith has been married to his wife, Jada Pinkett Smith, for 10 years ? a long time in Hollywood.

"It's like dog years when you're married here," she said. "That's like 50 years, right?

"What I found is divorce just can't be an option," explained Smith.

"It's really that simple. And I think that's the problem with L.A. ? there are so many options. So a huge part of the success for [Jada] and I is that we just removed the other options."

But there's more to it than that.

"We're like listen, we're going to be together one way or the other so we might as well try to be happy," added the 'Bad Boys' star.

DeGeneres also joked that Smith should retire from acting to take up a career in politics as presidential hopeful Barack Obama's running mate.

"I do think about [running for office] sometimes," Smith revealed.

"Right up until that Monday after the movie opens and I have a 100-percent approval rating. No politician is ever going to have that!"