Miami Dolphins running back Arian Foster has retired after eight seasons in the NFL, saying he is "walking away with peace" after a spate of injuries.
Announcing the decision on uninterrupted.com, Foster acknowledged that the uncompromising nature of the game that had taken a toll on his body and forced him into considering his future.
Foster wrote: "There comes a time in every athlete's career when their ambition and their body are no longer on the same page. I've reached that point. It's hard to write those words because this game has been everything to me...my therapy, my joy, my solace and my enemy.
"I've learned to love every facet of this game, from the peak of accomplishment to the gutter of criticism. And it all makes the ride worthwhile. I've been fortunate enough to play many successful years in this league. I've given a lot to this game and given up a lot for it. But it has returned to me more than I could have ever asked for."
The decision comes after British running back Jay Ajayi replaced Foster as the Dolphins' number one choice, having rushed for over 400 yards in his last two appearances.
Foster spent seven years with the Houston Texans after signing as an undrafted free agent in 2009. Originally cut and then re-signed to the practice squad, it took Foster until late November before he made his debut.
In his time in Houston, the running back made the Pro Bowl four times, and led the league in rushing touchdowns twice (2010, 2012).
However after a run of injuries, which saw his time on the field minimised to just four games in 2015, Foster was cut by Houston and signed with the Dolphins. He made an immediate impression on his debut with 100 yards of total offence in week one against the Seattle Seahawks, but after another soft tissue injury, the 30-year-old has decided to walk away from the game.
"My father always said, 'You'll know when it's time to walk away'. It has never been more clear than right now. I'm walking away with peace. I know it's not commonplace to do it mid-season, but my body just can't take the punishment this game asks for any longer.
"I want to thank the Miami Dolphins, with everything in me, for allowing me to bow out with grace and making this process as easy as possible."