Sometimes, the longest-lived players in the NFL are also the best. Think Mike Kenn, the Falcons legend who should be a Hall of Famer, and who leads the team in games played.
At the running back position, I don't think you could argue that the player who leads all others in games played is a true great. He was, however, a remarkably solid and useful player during his tenure with the team, one who earned every contest he played in and then some. He was also more or less universally beloved by the fanbase, if that gives you a further clue, and is someone that most fans probably remember well.
You'll all know the name once you hear it or discover it, so now give us your guess.