Will Smith and Jada Pinkett Smith's advice for a successful marriage is to "keep on trucking". The couple have been married since 1997 and they believe the secret to a happy relationship is to simply stick with it through the "tough patches". Will told 'Extra': "Just stay in it," while Jada added: "Stay in it. Keep on trucking. Marriages go through many different cycles and stages and it gets better and better and better and you will go through some tough patches some really bad ones that are going to make you want to quit, but don't!" Will has previously credited the couple's almost 20-year marriage to not quitting and admitted that it has been "the most difficult, excruciating thing" that he has ever taken on but insisted it was all worth it. He explained: "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, excruciating thing that we have ever taken on in our lives. And, you know, were just not quitters. "We only ever worked on ourselves individually and then presented ourselves to one another better than we were previously."