PHOENIX — Marshall Faulk's decision was easy after spending last year working for the NFL Network: At 34, his body is more suited for a television studio than for the rigors of playing running back.

After sitting out last season because of a knee injury, Faulk officially announced his retirement Monday. He's ninth on the NFL's career rushing list, 33 yards behind Jim Brown, who at one time was the standard for the position.

Faulk is fourth in combined yards from scrimmage with 19,154 yards and his 6,875 yards receiving are the most ever among running backs.

"Just being around the game last year, I realized how much I love it," Faulk said. "But my health is everything. And I didn't want to return if I couldn't get through a full season. It all came together when a close friend asked me 'How many 34-year-old running backs are there?"

Faulk starred at San Diego State, where he rushed for 386 yards and seven touchdowns in his first game, and led the nation in rushing as a freshman.

He was the second pick overall in the 1994 draft by Indianapolis and was offensive rookie of the year that season.

He was traded by the Colts to St. Louis in 1999, where he became part of "The Greatest Show on Turf" with quarterback Kurt Warner and receivers Isaac Bruce and Torry Holt. The team won the Super Bowl after the 1999 season and was upset two years later by New England in a Super Bowl that many critics thought the Rams would have won had Faulk carried the ball more often.

Faulk noted Monday that he had an unusual role in the development of that team — the injury during a 1999 exhibition game in San Diego to Trent Green that forced the Rams to go with Warner, an untested, undrafted free-agent backup at quarterback.

"There's kind of an unwritten rule among veterans in those games that when the play is over, you stopped," Faulk said. "I was blocking on Rodney Harrison and we had some things going between us. But I kind of let up and he kept going and he hit Trent. So when Kurt was forced to play, I kind of felt responsible and really wanted to make up for it."

He did.

He was voted the league's Most Valuable Player and offensive player of the year that season and won the offensive honors the next two years also. In that 1999 season, he ran for 1,381 yards and a 5.5 average and caught 87 passes for 1,048 yards.