Chris Borland
in 2014, the 49ers picked Chris Borland in a third-round draft pick. He went on to play an incredible season in San Francisco but only one year later retired due to health concerns. He admitted that it was not worth the risk to continue playing.
Lynn Swann
Swan was a four-time Super Bowl champion with the Steelers and had more successful endeavors than most football players do in their entire lives. However, despite still being at the height of his career, he chose to retire and work as a broadcaster.