Brian Urlacher announced his retirement from the NFL after 13 seasons Wednesday, ending what many believe was a Hall of Fame career as an iconic Chicago Bears linebacker.

"After spending a lot of time this spring thinking about my NFL future, I have made a decision to retire," Urlacher said in a statement he posted on Twitter. "Although I could continue playing, I'm not sure I would bring a level of performance or passion that's up to my standards. When considering this along with the fact I could retire after a 13-year career wearing only one jersey for such a storied franchise, my decision became pretty clear."

The Bears parted ways with Urlacher after last season when the two sides couldn't agree on a new contract. Urlacher became a free agent and had said he still had some football left, but chose to retire after briefly testing the free-agent market.

"I want to thank all of the people in my life that have helped me along the way," Urlacher said. "I will miss my teammates, my coaches and the great Bears fans. I'm proud to say that I gave all of you everything I had every time I took the field. I will miss this great game, but I leave it with no regret."

Urlacher told "The Waddle & Silvy Show" on ESPN 1000 that he's happy with his decision and will be filling out his retirement papers in the immediate future.

"I made my mind up a long time ago," Urlacher said. "It wasn't like an overnight decision. But I feel great about it. It's nice to have it behind me now and go onto the next stage of my life, whatever that may be. I thought it was time.

"I didn't want to put another jersey on for any other team. Obviously, it wasn't going to be for the Bears this year, so I thought it was the right thing to do to shut it down."

Urlacher enjoyed a very close relationship with former coach Lovie Smith, who was fired after last season and replaced by Marc Trestman. He was asked if he thought he'd still be with the Bears if Smith were still the coach.

"One-hundred percent, I think so," he said. "My want-to would be there more, as well. I think my desire to want to play for the Bears and still be there with his staff and my teammates would be a lot more as well. I love playing for him. He made football fun. He made our locker room fun. Our meetings were a blast, and everyone looked forward to going to work, every day."

A call to Smith was not immediately returned.