Definately try your local dog club for some classes. Even if he has basic training already its good socialization and structure. My 11 year old dog has always been very well trained so most of her life she hasn't been corrected a lot and I've let little things slide. Now I'm thinking of taking her to another class so she can remember just who's boss. Obedience classes aren't just for teaching puppies the basics and never using them again. They're great little brush-ups throughout life. The one thing I don't like are Petsmart classes. They overcharge from what I've heard ($200 as compared to $75 at the dog club) and I don't like when I see them in the store. They have the owners walk the dogs around the store for like "heel" exercises, but they can't see what the owners are doing right or wrong because they are walking around the aisles in and out of view of the instructor. If you're paying money for classes, go to professional dog handlers. Don't go to a retail store and pay more for a high school dropout who's watched a video on obedience training.

You may want him on glucosamine already since he'll be big. I believe if you wait until a dog is already developing arthritis, its too late to do a whole lot of good with supplements. An ounce of prevention is worth a pound of cure. Be sure to have him on a good diet too.