Former Chicago Bears wide receiver Johnny Knox has decided to give up trying to revive his career because of a lingering back injury.

Knox, who missed the 2012 season on the physically unable to perform list, was waived by the Bears on Tuesday.

"As an athlete, you don't want to give up, you want to keep on fighting. That's how I've always been," Knox told the Sun-Times on Wednesday. "But it's been on my heart for a while. I know how my body feels, and I know I'm not going to be the same and perform at the ability that I used to.

"So I'm moving on and going forward."

Knox suffered a back injury against Seattle late in the 2011 season. He described the injury as the worst pain he had ever felt. He missed the entire 2012 season after undergoing spinal fusion surgery.

"He had to work himself back up to where he could even walk," former Bears assistant coach Darryl Drake told the Chicago Tribune. "He had to work to get himself up out of bed. Hopefully, he'll continue to work and get himself back to where he can have the quality of life that he needs to have."

Knox ends his career with 133 receptions for 2,214 and 12 touchdowns. He participated in the Pro Bowl as a rookie in 2009.