Will Smith describes marriage to Jada as 'grueling' and 'excruciating'... but says they refuse to 'quit' after 20 years together

Will Smith and his wife Jada Pinkett Smith have been together for 20 years.

And at the Los Angeles premiere of his film Concussion on Monday, the 47-year-old spoke to Entertainment Tonight about how they keep their relationship so strong.

'We've been married 20 years and we've been asking ourselves [what’s the secret to marriage] and really at the end of the day it’s just not quitting,' the star revealed.

'You can’t expect it to be easy,' Will continued, adding: 'It’s like our marriage was the most difficult, grueling, excruciating thing that we have ever taken on in our lives. And you know we're just not quitters.'

He also opened up on what he believes to be the secret to maintaining a good marriage, which is always working to be a better person.

'I would say is that we never went into working on our relationship,' He explained. 

'We only ever worked on ourselves individually, and then presented ourselves to one another better than we were previously.'