12. Andrew Luck – Retired at 29 in 2019

During the third week of the 2019 NFL preseason, Indianapolis Colts quarterback Andrew Luck shocked the NFL world by announcing his retirement. His retirement was even more stunning given the fact that, with the duo of Luck and head coach Frank Reich, the Colts were considered by many to be a dark horse pick to win the AFC by many around the league

As the news emerged, Luck gave a public statement about the news, in which he cited his fatigue from constantly rehabbing the various injuries he sustained over the course of his 8-year NFL career. In that span, Luck sustained torn cartilage in 2 ribs, a partially torn abdomen, a lacerated kidney, a torn labrum in his throwing shoulder a lingering ankle and calf injury (that ultimately led to his retirement), and at least one documented concussion.