Barry Sanders was one of the greatest running backs ever. He and Jim Brown are the only two tailbacks in NFL history to average at least five yards per carry on 2,300-plus career rushes.
Sanders is also known for the manner in which his career ended. In 1999, coming off yet another outstanding season, he floored the NFL by announcing his retirement.
Sanders' abrupt decision to retire was shocking, but it wasn't unprecedented.
Throughout NFL history, stars have walked away from the game in their prime. Injuries forced some out. Others were concerned about their long-term health or wanted to pursue other opportunities.