Dogs are animals that live in groups that are arranged from the top down. They are happiest when they know where they are in the group and who the leader is.
A human group is not a dog group, but dogs don't understand that and feel that they need a place in it.
A dog's place is NOT near the top. Think about a chain of command where humans are all generals and dogs are all privates. NO dog should ever be promoted above private because generals make the decisions and do not need challenges from privates.
A dog who does not understand his or her place may spend a lifetime being afraid or a lifetime disputing with humans. A happy dog is well-adjusted and knows not to try to raise his or her rank.
In order to make your dog aware of his or her place and happy in the group, use the long down as a training tool. It is a quiet way of maintaining humans at the top of the group. Try doing this exercise when the work of the day is over and your dog is ready for a quiet time --- right after exciting exercise, vigorous training, or that long walk may not be the best time!
1) Start by sitting on the floor next to your dog and gently putting the dog into a down position. He’ll try to get up so gently put him back down. Don't say anything at all just reposition your dog each time he attempts to get up. After 10 minutes, say “YES”, let him up and give him some treats. Do this every day for a week, increasing the time until you reach 30 minutes.
2) Next, sit in a chair and put your dog in a down next to you. Put the leash under your foot. If he tries to get up, gently reposition him. Start with 10 minutes and work up to 30. Say “YES” and reward when you are ending the exercise.
3) For another week, do the same thing EXCEPT sit in a chair (or your couch) across the room. Go back and reposition each time your dog tries to get up. Be gentle and do not say anything, not even "down" or "stay." Just be gentle and persistent. When you choose to end the exercise say “YES” and reward.
4) Next, try walking around the room, returning should your dog try to move from his down. For another week, walk and talk but not to your dog. You should be able to reach 30 minutes doing other things but keeping one eye on your dog. Reposition as needed.
5) If you have any problems with your dog completing the long down, start over or go back to the step that he was doing it reliably and start there again.
This is a leadership exercise and worth your time if it can help make your dog a happy follower of a kind and humane leader.