For Will Smith and his wife Jada Pinkett Smith, the secret behind their 20-year relationship is simple: Don't quit.
ET was with the actor as he walked the red carpet at the premiere of his new film, "Concussion," where he opened up about making his marriage a priority.
"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 47-year-old actor said of Pinkett Smith, who he first started dating in 1995 and then married two years later. "You can't expect it to be easy, it's like our marriage was the most difficult, grueling, excruciating thing that we have ever taken on in our lives. And you know were just not quitters."
"If there is a secret I would say is that we never went into working in our relationship," he continued. "We only ever worked on ourselves individually, and then presented ourselves to one another better than we were previously."
See Will Smith through the years:
The star also recently revealed to ET about the unexpected impact his latest role played in his life. In "Concussion," Smith plays Dr. Bennet Omalu, a forensic neuropathologist who was the first to discover chronic traumatic encephalopathy in football players in the new movies, but admits he had some reservations about making the film because he's a "football dad."
"As a parent, my son played football. I loved it. I watched him," Smith said. "I had no idea of the long term potential negative impact of repetitive head trauma."
To see how else his new role changed him, watch the video below.
Also see Jada Pinkett Smith's look from the Latin Grammy Awards:
More from AOL.com:
'Flip or Flop' co-host Tarek El Moussa saved by fan who spotted cancerous lump
Bristol Palin is naming her baby girl Sailor, jokes Kristin Cavallari stole her idea
EXCLUSIVE: Justin Bieber cancels 'Late Show' and Thanksgiving Day Parade appearances for personal reasons