Moving Well = Feeling Well
Your dog only wants to know one thing: How much energy can I move with you?
When your dog's prey or play drive is aroused, they need to MOVE. When your dog's fight or flight energy is activated, they need to MOVE. When your dog feels attracted to another dog, another person, or a novel situation or environment, you need to be the magnet for their energy. Asking your dog to sit for a cookie, to "look at me," or to lay down and maintain stillness does not satisfy the internal pull they feel to move.
Stress is emotion that didn't find MOTION. That is why your dog gets so leash reactive or has barrier frustration. So when your dog feels stress, and you give them an outlet for that stress, not only did you resolve the original problem, they are more likely to turn to you in times of stress to help them feel better. You become the manager of their stress, but you also give them tools to self-regulate; because helping them move well while pressurized actually calms their nervous system and increases their emotional capacity. So the idea isn't to always keep them "under threshold," but rather to teach them how to act (not react) when they feel themselves tipping over threshold.
In situations of high intensity, you will offer them resistance against which they can work to get food. You offer them a bite toy on which they can express the fight and bite that normally gets pent up inside as frustration. You can even simply run and play with them, as they would normally run and play with another dog to create a dynamic exchange of energy.
So the very last thing I ever want my dog to do in situations of high stress is to sit still and look at me. I want them to look to me for a solution to their stress. And I want to give them options. Even barking on command is a way to move stress. A dog who can bark coherently is much more likely to be in control of their body and their impulses.
Many people are at first confused by this system of training, because what they thought they wanted was to teach the dog: "No Jump, No Bark, No Bite." What they thought they wanted was a calm, quiet dog who doesn't even really act like a dog. But this rarely brings an answer to the stress of daily life. Dogs are basically living in captivity, as we are, away from the natural world and the natural movement or instinct to regulate as we might in the wild.
So let's give them a chance to express their energy: to bite the toy, to make contact with you, to run, to bark and chase, and even do constructive work. This freedom to move, and to move well under stress, is what will increase the likelihood that your dog will stay under threshold in times of arousal. That your dog will understand how to move, when to move, when and what to bite, how and when to bark, and how to play with a soft mouth.
This, in turn, will make your dog very happy, even joyful, like a supple puppy who is taking it all in with a sense of joy and ease. And you might discover your own inner puppy: in the joy of moving, creatively engaging, and finding yourself completely immersed in the present moment... Letting go of the need to control, and instead flowing in harmony with the natural energy presented to you by your dog.