James Harrison is retiring from the NFL after 15 seasons.

Harrison will turn 40 next month.

In an Instagram post, the linebacker wrote: "I've missed way too much for way too long...and I'm done. Many thanks to my family, coaches, the fans, and everyone who played a role in my football life."

Harrison, who signed with the New England Patriots on Dec. 26 after he was released by the Pittsburgh Steelers, had said in the week leading up to Super Bowl LII that he hoped to play another season or two.