Diaphragmatic breathing is the way to go.

I suffered a neck injury diving into our above ground pool as a teenager. It dramatically changed my wellbeing. Over the years I would have excruciating muscle spasms in my neck at least 2x/year. I would have to go on muscle relaxers and miss a couple days of work each time. I would constantly feel like my shoulders were by my ears. My chiropractor would tell me the secret to reduced tension in my neck was to diaphragmatically breathe, I'd try, but 2 minutes later my shoulders would be up again.

Then I read a different perspective.
Imagine your diaphragm contracting as it is pushing down when you breathe in- as it is expanding and pulling your lungs down;
Then just relax as your diaphragm is expanding as you naturally breathe out expelling your lungs as they are pushed back up.

Your diaphragm does the work while your lungs are passively pulled and pushed. My shoulders have never been more relaxed. Now whenever I feel stressed or chilled, I take time to do 10 deep diaphragmatic breaths. It's crazy how relaxing and warming it is

Today I was having an angina attack and didn't want to take many meds for it. So I laid on the bed and also as did @Lojeandres breathing from my diaphragm. I learned how to do it way back in Jr High during chorus. Our teacher was terrific making sure we did it correctly to help us with singing. With yoga I learned it a different way, between the 2 of them today it made sense to try. WOOHOO!! I did take 1 med, but just that one. Did it help? I think so. It also helps ALL of my muscles to really relax.

I always like a reminder to breathe. I saw a meme of someone saying something like take a big breath, see all better....