ENGLEWOOD, Colo. (AP) -- John Moffitt wasn't unhappy with a lack of playing time in Denver. He quit the NFL because he'd lost his love for the game and was tired of risking his health.
The third-year guard from Wisconsin called the Broncos from his home in Seattle this week to notify them he wouldn't be returning to the team following its bye.
Then he announced on Twitter that he was calling it a career, saying, ''Football was fun but my head hurts-haha kidding roger goodell. I'm on to new things, thanks to everyone along the way!!!''
The Broncos put him on their reserve/left team list on Tuesday when they activated center J.D. Walton from the physically unable to perform list.
They have five days to formally release Moffitt, who left more than $1 million on the table, including about $312,500 for the remainder of this season and $752,500 in non-guaranteed salary in 2014.
Moffitt, who signed a four-year contract for nearly $3 million after Seattle made him the 75th overall draft pick in 2011, said he knows teammates and fans don't understand how he could forgo the fame and fortune of pro football.
''I just really thought about it and decided I'm not happy. I'm not happy at all,'' Moffitt told The Associated Press in a phone interview from Seattle. ''And I think it's really madness to risk your body, risk your well-being and risk your happiness for money.
''Everybody, they just don't get it and they think it's crazy. But I think what I was doing is crazy.''
He said he didn't want to see things through this season for the shot at a Super Bowl.
''I don't care about the Super Bowl. I don't,'' Moffitt insisted. ''I used to. I mean, anytime I played this game, I gave my heart to it and I'm a person that does thing with his heart. ... I don't need the Super Bowl experience. I played in great stadiums and I played against great players. And I had that experience and it's enough.''
The Broncos acquired Moffitt on Aug. 20 from the Seahawks after he'd lost out on one of two starting guard spots in Seattle during training camp. He played in two games for the Broncos (7-1).
Moffitt, 27, made about $1.8 million before taxes in his 2 1/2 seasons in the NFL.
''I've saved enough. It's not like I'm sitting here and I'm a millionaire,'' he said. ''That's what I kind of realized. I'm sitting here and I got to this point and I was like, what is the number that you need? How much do you really need? What do you want in life? And I decided that I don't really need to be a millionaire.
''I just want to be happy. And I find that people that have the least in life are sometimes the happiest. And I don't have the least in life. I have enough in life. And I won't sacrifice my health for that.''
Moffitt stressed that he's not passing judgment on his former colleagues, saying, ''This is all my personal stuff and I respect this game and I respect the men in this game.''
Although Moffitt never had a history of concussions, he acknowledged all the blows he sustained in practices and games concerned him.
''I'm not trying to be the poster boy for 'Oh, I thought I should leave because of concussions.' I'm just saying, it's a valid point,'' Moffitt said. ''I love the game and I respect the game and everybody who plays it knows what they risk and I knew what I risked when I played, and I'm no longer willing to risk it.''
Moffitt majored in sociology at Wisconsin and said his world view was really shaped over the last couple of years when he began studying the writings of the Dalai Lama and Noam Chomsky.
Now that he's out from behind the NFL shield, Moffitt said he's looking forward to speaking his mind on the radio and in podcasts he's going to produce. He said he has plenty of opinions to share on everything from philosophy to politics, although he has less to say about sports.
He said he also wants to go on a diet now that he doesn't have to maintain his 319-pound physique.
Moffitt said the timing of his decision had nothing to do with Walton being activated from the reserve/PUP list, although ''I'm glad it worked out like that.'' And he said he felt bad his decision coincided with coach John Fox's heart operation.
He doesn't regret playing football, either.
''Obviously, I wish things worked out better in Seattle. I wish I played more there, but I loved college football. I loved being in Seattle playing football. It wasn't always the easiest, but I live here now and I'm thankful,'' he said. ''I look back and I'm thankful for the whole experience. That's enough for me.''
Moffitt said he wants to spend more time with his parents in Connecticut and with his girlfriend and her 5-year-old daughter in Seattle. He said his father is ''my best friend and I never get to see him.''
Moffitt said he'll miss playing in games and goofing around with the guys, but he's glad the rest of his NFL life is over.
''Once you tear away all the illusions of it, it's hard work. And it's dangerous work. And you're away from your family. And it's not good for families. It's very tough on families,'' he said.
Moffitt is also glad to leave the league on his terms.
''I'm ready to go to work and start doing other things right now,'' Moffitt said. ''So, it's a smoother transition and I'm still young enough to start a career and my body's healthy and I'm good. I look at it as a great start to life, you know?''
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