I have a big +wild dog , & I have run into similar situations .Dogs like that need 45 minutes of off leash exercise.Now I have to spend a small fortune driving my dog to a dog park every day.
Off leash is nice...but it doesn't have to be off leash, I used to walk my dogs every day for 1.5 hours, makes for a very relaxed dog and very enjoyable dog. Once relaxed the dog will give all his attention to you and will be more focused on training...not much walking these days though as my boys are getting a little up there in age and both are suffering from hip dysplasia.
Labs are one of the most energetic dogs there are and need a lot of exercise as pups or they will find something to do and mos the time its not good, well in the human world its not good, but in the dog world its FUCKING GREAT...hahahahaha, believe me I know what an energetic dog needs are...I have an English walker coonhound...one of the smartest dogs I've had the privilege to be around.
99% of dogs want to follow, however give them the opportunity and they will take the lead, its just nature of the dog.
there is a book on the market, quite old book called
"Mother Knows Best"
It is one of the best books on raising a pup...it will teach ya everything ya need to know.
GL