Muncie was traded by the Saints at midseason in 1980 to San Diego, where he played 51 games and was named to Pro Bowl rosters two more times, in 1981 and '82. In 2009, the club recognized him as one of the 50 greatest Chargers of all time.
His accomplishments on the field came despite cocaine use, and in 1989, five years after his retirement from pro football, Muncie was sentenced to 18 months in prison for a cocaine distribution conviction.
Thereafter, however, he began sharing his life story with at-risk youth, highlighting his struggles with drug abuse. He created the Chuck Muncie Youth Foundation, the mission of which was to offer children mentoring, educational assistance and counseling.
"His work with at-risk youth, the Boys and Girls Clubs and his foundation were the things that really made him shine," Muncie's daughter, Danielle Ward, said in a written statement provided by Foster.
"He was a star on the football field but his most impressive work was done in the second chapter of his life where he lived his life with great transparency," added Muncie's former wife, Robyn Hood. "He simply wanted others to learn from his mistakes. He carried that message with him everywhere he went. And as a result, he changed the lives of hundreds of kids. He made a difference."
Muncie's 43 touchdowns for San Diego, and 19 touchdowns in a single season, both rank second in Chargers history, eclipsed only by LaDainian Tomlinson.
"Everyone at the Chargers is deeply saddened by the passing of Chuck Muncie, one of the greatest running backs in Chargers history," the team said in a written statement. "We will remember him as a tremendous athlete with a larger-than-life personality. It's a sad day for all of us and all Chargers fans."