Harrison says he's ready to spend more time with his friends and family.
The five-time Pro Bowler and 2008 NFL Defensive Player of the Year is known for his wild workouts, and he appeared at the gym soon after his announcement.
Harrison helped the Patriots reach the Super Bowl, where they ultimately lost to the Philadelphia Eagles.
Donovan Mitchell says he 'feels fine' after hurting toe
It was his first playoff game with the Thunder since being acquired in a trade with the in in the offseason. Mitchell finished with 27 points and 10 rebounds in his playoff debut, a 116-108 Thunder win.
The New Gmail Is Definitely Going To Have Self-Destructing Emails
Finally, an email can be locked behind a two-factor authentication process to ensure that only the intended recipient can read it. Snooze an email - You tag an email with a time stamp and it disappears from your inbox and reappears at the time you've chosen.
US pastor faces terror charges in fraught trial in Turkey
The indictment says the charges are based on evidence obtained from Brunson's phone, as well as information from witnesses. Also in court were Sam Brownback, the US ambassador at large for religious freedoms, and US Senator Thom Tillis.
Harrison, 39, posted a collage of pictures of his two sons and noted he's "missed way too much for way too long ... and I'm done".
Be sure to do an extra bench press and set of leg squats for James Harrison on Monday.
Harrison was undrafted out of Kent State in 2002.
And what did Harrison do with his newly found free time? He announced in August he was done, but Harrison returned to the field in September.
Harrison, who turns 40 next month, previously retired in 2014 after a one-year stint with the Cincinnatti Bengals. However, he had a change of heart and continued to play on for a few more seasons. He had two sacks in his debut with New England in the 2017 regular-season finale and added seven more tackles in the playoffs. The Ravens sent him to NFL Europe before eventually releasing him.