When you feel happy your brain immediately projects on to your muscles, whatever you feel, you are putting weight over your face & body and it tugs the muscle called zygomaticus and it connected to the emotional areas of the brain. It goes the other way as well, it’s called bi-directional, means how your feel is projected on to your body. What you do with your body actually projects back to the brain affects how you feel. One of the simplest ways to actually feel relaxed is to relax your shoulders, straighten your spine and then move in a really slow way purposely but slowly and actually and what it does your body is telling your brain that am relaxed so actually alters your brain chemistry. Similarly in the case of stress, when you feel stressed sometimes you start walking very fast.
What happens if you stop using your muscle? it shrinks and you feel uneasiness in your body’s postures because you feel that way. When you feel anxious, resources go to the hanging brain, so to overcome this you need to project these resources to the forebrain. The really cool exercise for diverting the direction of resources in the brain is to move your body or say start dancing effectively. Isn’t amazing how we can use our body even to overcome any anxious moments.