You got real good advice but I have to add a little on some of it.

Leaving the leash on the pup and letting it drag it around all day is what I do, but labs(mine anyway) are bad about chewing the leash in half if it gets caught on something.
I would try putting a real light weight chain on the pup. You know that ones that don't hardly weight anything? Cut it to where its only about 4 feet long.

You could also tie the pup in a safe place where you can see it and let it raise hell all it wants. I would suggest putting one of those ground stakes all the way into the ground and then put the pups chain on it.

Whatever you do, I wish you luck.

April and the gang