My throat was closing up, it felt like I was trying to breathe on the top of Mt. Everest after running a marathon and my heart was beating out of my chest... Pacing the room wasn't helping and I was worried I would pass out at any given moment.
That's what my latest anxiety attack felt like. I knew I needed to figure out how to breathe or I would end up panicking even more, so I thought back to what my counselor told me. "Box breathing. Use your hand and make a box with your pointer finger. When you're going up you breathe in for 4 seconds, hold it when you're going across, exhale for 4 seconds going down and back across holding for four seconds."
HealthLine lays it out like this...
Sitting upright, slowly exhale, getting all the oxygen out of your lungs. Focus on this intention and be conscious of what you’re doing.
Inhale slowly and deeply through your nose to the count of four. In this step, count to four very slowly in your head. Feel the air fill your lungs, one section at a time, until your lungs are completely full and the air moves into your abdomen.
Hold your breath for another slow count of four.
Exhale through your mouth for the same slow count of four, expelling the air from your lungs and abdomen. Be conscious of the feeling of the air leaving your lungs.
Hold your breath for the same slow count of four before repeating this process.
The crazy thing about this type of breathing is that Navy seals use it as well! It's a huge help and I pray it helps you when you need to calm your mind and body.
Here's one more article on it: https://thepreppingguide.com/box-breathing/