You can increase or decrease your anxiety and stress levels by changing how you breathe. I have spent the last few decades being amazed at how something so simple as normal breathing can be so lifechanging.
It all comes back to letting those neck and shoulder muscles that go between your head and shoulder girdle relax instead of having to do weight lifting as they lift your rib cage up and down to breathe. Then let your diaphragm muscle do the work of drawing the air down into your lungs. You will notice your tummy gently moving in and out with each breath. So no more of that awful ‘shoulders back. chest out, tummy in’ that wouldn’t let any diaphragm movement happen easily.
See my article on breathing patterns, and I have a free relaxation and breathing on my home page to help you get the feel of it.