When my dog was 8 months, I went to a wonderful trainer for a private session related to a behavioural issue. This woman was a many title winning trainer of sheep herding and agility and obedience border collies. Plain spoken, experienced, and incredibly observant.
In exasperation, offhand as we talked about other stuff, I complained that my dog did not know how to settle. She wanted me to go go go ALL THE TIME. She would down stay, but she would just stare at me, not relax and hop up the moment I even shifted.
Trainer kinda smiled and said yeah,that's what these high drive/high energy dogs are like. She said - there is no point in trying to physically exhaust one of these dogs, you could do nothing but that and the dog would still want more! She said - tell your dog what you want.
My dog was on leash, at a down stay at my feet, watching me, poised to hop up at a moment's notice. She told me - there, she looked away. Mark that, drop a treat. I did. Dog hopped up after the reward, I put her back in a stay. Trainer said as we continued to talk - look, her ear settled back a bit. Mark that, drop a treat. She rolled on her hip a bit - mark that. Etc.
You can train a dog to LOOK relaxed by marking when it shows signs of relaxation. You know how they say when you make your face smile, it lights up some of the same areas of the brain as when you are actually happy? If you make a dog act like it is relaxed, it does the same thing.
Anyway, she had me keep doing that as we spoke. Very quickly, my dog was sprawled on the floor. New environment, new person, tons of awesome new smells (Sheep! Dogs! People!) And my 8 month old crazy dog was relaxed on her side on the floor. That, right there, was worth the $60 private lesson fee and more, and it wasn't even what I was there to learn.
There is something called the relaxation protocol and it's a more formal version of this that I started to do with my dog. Marking physical signs of relaxation so the dog learns to quickly go from excited to relaxed and do so on cue (I use settle).
Awesome trainer also suggested I have my dog do a down stay 20, 30 or more minutes at a time while I do other chores around the house, and reward signs of relaxation. Teach her that her job in the house is to relax. She said this was both mental work to tire the dogs brain out, and teaching an off switch. She was right, and it was like I had a completely different dog within days.
Now - at 2, my dog is generally very relaxed when we aren't working/playing and, even in public, I can say 'settle' and she relaxes back on her hip, and often puts her head down. I had her in a class today, said 'settle' and suddenly she went from turned on and staring, waiting eagerly for my next command, to relaxed on her hip, lying on the ground beside me. Magic. Absolute magic.