The 31-year-old Glenn, a first-round draft pick out of California in 1997, started 154 regular-season games during his 10-year career. A steady blocker on the left side of the offensive line, he was a main reason quarterback Peyton Manning was sacked just 15 times last season and a league-low 176 times since Manning joined the team in 1998.
"Making this decision, I had to step outside that (team) role and see what was good for myself and my family, and that was hard to do," Glenn said at a news conference at the Colts' headquarters. "Hearing people talk and players asking me to reconsider and reminding me of some of the things and what I mean to this team, it hurts. It really hurts.
"But I'm real convinced this is what I should do."
The 6-foot-5, 332-pound Glenn was second to 11-year veteran receiver Marvin Harrison in years of service with the Colts.
He reportedly had hinted to teammates he was considering retirement after the Colts' Super Bowl win over Chicago, and Indianapolis took Tony Ugoh, a three-year starter at Arkansas, in the second round of the NFL draft in April.
|Tarik Glenn calls it a career after 10 years with the team that drafted him in '97. (Getty Images)|
By the end of last month, he said, he realized his passion for the sport had diminished.
"It would not be fair to the team or the game not to give it my all," he said.
Glenn, who was born in Cleveland but grew up in Oakland, Calif., said he would remain in Indianapolis and work in the community and with a nonprofit charity organization he started in 2001.
He said Manning and others tried to talk him out of retiring, but when their efforts failed, wished him well.
"That's OK," he said. "I wanted to hear what everybody else's feelings were, because it was affecting everybody. ... I hate the fact I feel like I feel, but I've just got to move on."
The Colts have lost four other starters -- cornerbacks Jason David and Nick Harper, former Pro Bowl linebacker Cato June and running back Dominic Rhodes -- through free agency. They also released receiver Brandon Stokley and defensive tackle Montae Reagor, starters until they suffered season-ending injuries in 2006.