Los Angeles, Nov 25 (IANS): Actor Will Smith, who has been married to fellow Hollywood actress Jada Pinkett Smith since 1997, says their relationship has been "gruelling".

"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. You can't expect it to be easy. It's like our marriage was the most difficult, gruelling, excruciating thing that we have ever taken on in our lives. And you know we're just not quitters," Will told etonline.com.

Of the secret behind a good marriage, Will said: "I would say is that we never went into working on our relationship. We only ever worked on ourselves individually, and then presented ourselves to one another better than we were previously."

The couple has been the subject of numerous divorce rumours in recent months and in August, Will took to Facebook to rubbish the speculation.

"So, in the interest of redundant, repetitious, over & over-again-ness... Jada and I are... Not gettinf a divorce! (sic)," he had said.