He’s three months shy of his 32nd birthday, entering his 11th NFL season and coming off the second major injury of his career, so of course Nate Burleson is approaching this fall with a heightened sense of urgency.

His window to win is now, and there’s no telling what his future holds.

But Burleson, who pushed himself through two-a-day workouts in his native Seattle this off-season to return ahead of schedule from the broken leg that limited him to six games last year, said something struck him about the Lions’ revamped roster when he showed up for the start of organized team activities this week: His teammates shared his sense of purpose.

“There is a different sense of seriousness,” Burleson said Wednesday, after the second of 10 OTA practices the Lions will hold over the next three weeks. “I think we’re a little bit more focused. Everybody understands that, realistically, there’s a window of time for everybody here. Coaches see it. Players see it. Whether you’re old, young, a rookie, if things don’t shape up in the direction we need them to, then there’s going to be changes, and nobody wants that.”

Already, the Lions have undergone plenty of change since last year ended with a disappointing 4-12 record.

Gone are cornerstone veterans such as Jeff Backus, Jason Hanson and Kyle Vanden Bosch, and in their place the Lions added youth, hope and even a little star power in running back Reggie Bush.

Burleson said last year served as “a definite reality check” for players that may have taken too much for granted coming off an uplifting playoff appearance in 2011, the organization’s first in a dozen years.

“I remember a couple years ago, we were just foaming at the mouth every chance we got,” Burleson said. “We were in an alley fight and we loved it and we relished in those moments.

“Last year, I didn’t see that as much. We had glimpses of it. After having the season 4-12, I think guys are back foaming at the mouth. We feel like we have to put our backs against the walls and fight our way back to the top again, which is good ’cause we play better like that.”

The Lions are still a long way from playing games that matter, but they had near perfect attendance at Wednesday’s voluntary workout, and linebacker Stephen Tulloch said it has been that way most of the off-season.

Safety Louis Delmas, who’s rehabbing his knee in Florida, and running back Jahvid Best, who’s not likely to play again because of concussions, were the only members of the 90-man roster not at the Lions’ Allen Park facility Wednesday.

“There’s a sense of urgency, I’ll tell you that,” Tulloch said. “Guys are working. I can honestly say it’s probably about 98% attendance rate week in and week out this off-season training, which is probably the best since I’ve been around the league. And guys, they want to improve, they want to get better. Four and 12 didn’t sit well with me or my teammates, so the fact guys are working here and they have their blinders on and we’re focused goes a long way.”