Will Smith says his upbringing as a football-loving Eagles fan made it difficult, at first, to accept the science behind his new movie "Concussion."

Smith plays Dr. Bennet Omalu, the Nigerian-born Pittsburgh pathologist who discovered degenerate disease (he named it CTE) in the brains of deceased football players, making him an enemy of the NFL.

"My son played for four years, and it was some of the most beautiful time that we've had together," Smith, 47, told ABC News. "This is not an anti-football movie. I love football, I grew up in Philly. I'm a football fan, my Eagles. It was a very inconvenient truth."

As an actor, the role intrigued him. Omalu was a working pathologist when he began to discover damaged tissue in the brains of former players, many barely 50 years old. Omalu become a crusader when the league began to attack his findings, pushing him to compile an overwhelming amount of evidence.

As a parent, the script alarmed him.

"The reality of the science, and as a parent I knew that I didn't know when my son was playing football, I didn't know that repetitive head trauma from the game could cause long-term brain injury. You can make any decision that you want, but for me, as a parent, I was compelled to deliver this film to the world."

Omalu examined the brains of former Steelers Mike Webster (played by Philly's David Morse), Terry Long and Justin Strzelczyk, and found them full of toxic proteins that cause dementia and other symptoms. His work on former Eagle Andre Waters was decisive in building a case for the danger of repeated concussions. Waters emerges as an important character in the film: An ailing Waters is seen asking for help from an NFL representative and being turned away before committing suicide. CTE was found in his brain. (Reporter David Gambacorta talked with former Eagles players about their teammate in the Dec. 15 Daily News).

"Concussion" was screened recently for former players by the NFL Players Association, and it prompted strong reaction.

Former player Keith McCants told the Sports Illustrated website MMQB: "This movie touched my soul. I watch this movie, and I know we were paid to hurt people. We were paid to give concussions. If we knew we were killing people, I never would have put on the uniform."

Former star receiver Willie Gault told CBS Sports: "Every single football player in this country - NFL, college, high school, youth - needs to see this movie," Gault said. "If I had seen it while I was a player, I think I still would have played football, but I would have played it differently. I would have had a different mind-set."

The NFL has responded to the movie by saying rule changes and concussion protocols have reduced the incidence of concussions by 30 percent in three years.

Kevin Hart helps kids, salutes troops

Another Philly-born movie star, Kevin Hart, joined "Ride Along 2" co-star Ice Cube and Carolina Panthers quarterback Cam Newton to visit children in the Charlotte, N.C., area on a "surprise sleigh," giving gifts and donations for the renovation of high school athletic facilities.

The previous day, Hart and Ice Cube visited troops at the Joint Expeditionary Base in Norfolk, Va., and hosted an advance screening of "Ride Along 2," slated to arrive in theaters Jan. 15.

"I know for myself, and I can speak for [Ice Cube], I want to say a major thank you for doing what you do to protect myself and my family," said Hart.

- Daily News wire services contributed to this report.