Is this the final season for Ray Lewis?

The AFC North blog doesn't give birthday shout-outs, but this one has special significance.

Ravens linebacker Ray Lewis turns 37 today, which could be the magic number for him. In April 2011, Lewis hinted at a target date for his retirement when he told the NFL Network, "I can’t see myself playing football past 37.”

Lewis made it clear after Baltimore's AFC Championship Game loss that he was returning in 2012, but there has to be questions about whether he will play beyond this year. At some point, Lewis is going to have to say goodbye to football, although there haven't been any recent indicators he will be calling it quits anytime soon. His contract runs through 2015, and the Ravens showed confidence in Lewis when they once again didn't draft his eventual replacement in April.

Lewis started off strong last season and was among the NFL's top inside linebackers in the first half of the 2011. Then, after missing four games with a toe injury, he seemed to wear down toward the end of the year. During the playoffs, Lewis didn't sound close to retiring when asked about his future.

"Football is too fun for me, man," Lewis said in January. "Whenever God says time is enough, then it's enough. But when you're having the fun that I'm having, and you're playing at the level I'm playing at, do it until you can't do it no more."

Lewis has been one of the league's top Iron Men. His 222 games played is second-most among active players, ranking only behind a kicker (Jason Hanson). He is the longest-tenured Raven on the roster by six seasons (safety Ed Reed is second).

No other great middle linebacker has played as along as Lewis. Mike Singletary retired after 12 seasons with the Chicago Bears before his play declined. The Pittsburgh Steelers' Jack Lambert walked away after 11 years because of a severe toe injury. And the Bears' Dick Butkus stopped after nine seasons because of knee injuries.

Lewis is now entering his 17th season in the NFL. And, after turning 37 today, you have to wonder whether this will be his last.