Let's get back to the point. The point being its a lab. They are a destructive breed. I have owned many of them in my life, and some are way worse than others. You can run the dog as much as you want and some will still be destructive when left alone for as little as a few minutes. I had one who I hunted and ran everyday. At just over a year old I remember it ate and swallowed a remote for the tv as I went to get a drink. It was just a few minutes. All puppies should be crate trained until you know they don't chew. Yes, the dog should have an outlet for its energy, yes it should have toys, but I have yet to meet a lab that didn't chew no matter how much it was run. They tire easily from runs being a larger boned dog, but they recoup fast and you are never going to run and exercise a lab to the point you can leave it and not worry about destruction. Bottom line is exercise, start indoor training, give it toys, but crate train it.