BOSTON — How much longer can Zdeno Chara keep this up?

The Boston Bruins defenseman – and leader in ice time – will turn 42 this season, and sooner or later the window will close on his opportunity to skate around the ice again with the Stanley Cup. For his teammates, that means focusing on this season as their best and possibly last chance to win with him.

“The older you get, it’s just about winning,” said David Krejci, one of five holdovers from the franchise’s last title, in 2011. “We know that we’re not going to be playing in the league for 10 more years, but we have maybe three, four, five years left, who knows, but this is it. We worked really, really hard this summer to get the job done this year.”

Chara was already an eight-year veteran and two-time All-Star when he signed with Boston a dozen years ago, and the Bruins built a contender around him that went to the Stanley Cup finals twice in three years. (They lost to Chicago in 2013.)

Patrice Bergeron, Tuukka Rask, Brad Marchand and David Krejci are the only other players remaining from the 2011 champs. Bergeron is 33, Rask and Krejci will turn 32 during the playoffs, and Marchand will turn 31. (Steven Kampfer was traded away in 2012 and rejoined the Bruins this summer; he just turned 30.)

Charlie McAvoy, the 20-year-old defenseman paired with Chara for most of his career, has seen players come and go and values the stability brought by the core.

“As long as we have those veteran guys the culture will always be the same, I really believe that,” he said. “I really think it could be another special year. You bring back all these guys, the veterans, it could be an awesome year and I’m really excited to get it going.”

Here are some other things to look for from the Bruins this season:

SOPHOMORES

Helping to take some of the pressure off the aging core is a group with about one year of experience, led by McAvoy. Also among the sophomores are Jake DeBrusk, Danton Heinen, Matt Grzelcyk and Sean Kuraly.

“None of us are forecasting a setback, I call tell you that,” McAvoy said. “Something about the experience of having a full season, playing a few playoff series now, seeing that element. I can use all those things to allow me to come in and play great hockey from the start. That’s my goal.”

Those five combined to score 151 points (48 goals, 103 assists) last season.

MORE NEW BLOOD

Joining the youth movement are players in their first full season like Jakob Forsbacka Karlsson, Ryan Donato and Anders Bjork. Dante Carlo has two years behind him but is just 21.

“You need those young guys,” Krejci said. “And our young guys are fast, they’re good, they’re smart, they make plays. They deserved to make the team last year and I’m looking forward to what they’ll bring again this year, one year under their belts.”

IN NET

Rask returns for his 12th season but he has a new backup.

Jaroslav Halak signed a two-year contract to come to Boston from the Islanders, where he started 49 games last season and had a 3.19 goals-against average. He replaces Anton Khudobin, who had been the backup for two years and started last season 7-0-2 filling in while Rask had a concussion.

The fast start led fans to call for him to replace Rask, when he won just three of his first 13 games. But the 2014 Vezina Trophy winner did not lose a game in regulation from Nov. 26 until Feb. 10, finishing with a 34-14-15 record and a GAA of 2.36.

LONG TRIPS

The Bruins played two exhibition games in China against the Calgary Flames, with Cassidy and half the squad heading over to Shenzhen and Beijing for a week while the rest of the team stayed home. The split squad wasn’t ideal, but the Bruins started the 2010-11 season with two games in Prague and went on to win the Stanley Cup.

Cassidy said that would be a nice precedent to follow.

“Well if it’s a repeat of ’11, yes,” he said. “I’d love that to happen, trust me.”