Anyone raising Labs, or other large breeds?

Labs are dogs that are bred to have a job. I haven't had a lab in over 10 years now so the ages aren't as fresh in my mind. Our German shorthair pointer ( another gun dog breed like yours) was the same way and so is our German Shepherd. They settle down a lot after two or three years. Since you're already walking him a lot, maybe a little training time teaching him some new tricks in between will keep him distracted and busy.

I have several good friends who have labs, they are very slow to mature. Usually between 2 and 3 years old. They are also a very active breed so those two walks may not be enough. As they say a tired dog is a good dog. You should look into other ways to burn some energy. In addition to physical, mental activities will also work.

I've had GSD's that are more active and need a "job" otherwise they get into trouble!

With labs they tend to need activity as well. Along with their walk, how about a game of fetch with a toy or ball or even a game of frisbee? It's their natural drive to chase something!

Labs are very exuberant and enthusiastic about everything. 8)

But they usually mellow out a little between 2 and 3 years old.

Controversial, and I'll probably get bashed, but an e-collar used appropriately, for training and correction purposes, can do wonders. Used correctly, the dog learns what acceptable and unacceptable behaviors are in a very short time and you'll have the pet of your dreams.

ETA - I need to clarify, I would only recommend this as a last resort, for only specific training issues when traditional obedience training isn't working. For instance, our dog is very smart and learns quickly. He did really great at his obedience classes and when we practiced, but he continued to counter surf or sneak into the utility room at eat the cat's food. His natural, instinctive drives were more powerful than our repeated "no's". redirects, or staging a bunch of empty cans to fall over and startle him. We talked with our trainer, who is an an expert in his field and also breeds and trains dogs for K-9 units and competitions. He suggested the e-collar. I was reluctant to use it. I didn't want to hurt my dog. The day came for us to use it. We had it set on a low-moderate frequency and observed the dog in order to catch him in the act. All it took was one correction at each misbehavior and he never did either thing again.

We had a similar experience outdoors. At his prior owner's home he got out of their fenced yard during a party and took off running. Party guests took off on foot and by car, trying to find him. He ended up several miles from home. Contrast that to us having a large yard (slightly under an acre) on a corner lot, and no fence. Our dog wants to be friends with anyone and everyone, plus he gets easily distracted by squirrels and bunnies. We want our dog to be able to safely enjoy the outdoors, but also don't want a fence. We've worked with him with perimeter training, but again, the drive in him to chase a bunny or squirrel could be stronger and he'd end up in the street. One time with the e-collar was enough for him to learn that the street (and the neighbors' yards) is off limits unless he's on a leash and we're specifically out for a walk. He learned his boundaries when we're outdoors so now we can be out there watering the flowers, washing the car, walking down to the end of the driveway to get the mail, you name it, and he's always nearby.

Thank you all for your replies. We have tried to teach him to fetch, but from the moment he came here, he has loved to be chased. Its hard to get him to put anything down, because when we are chasing him, that's exactly what he wants. Surely I can last another year or so, lol.

Another Lab owner here. Our present girl is 7 and still has lots of energy. Unlike our other Labs, she didn't settle down until she was 4. Our others were much more settled at 2 (they were yellow and black, this one chocolate). We walk this dog at least 4 miles a morning. She swims every day during summer and loves to play frisbee on land and in the lake. A run with other dogs issue a great way to tire them out. When they walk with us, it's at our pace. When they play with other dogs, it is much faster. Good luck! LM