I have severe debilitating anxiety attacks that come about for no reason. I work from home so I am lucky enough to be able to "take care" of my anxiety in private and in the comfort of my own home.
If you have an attack and are in a private place, I have a technique that almost always takes my anxiety away or down to a level where I can easily breathe and calm down.
The easiest and most comfortable way for me to do this is on the sofa/couch. Facing the the back of the sofa, I place my rear-end against the back cushions, my feet rest at the top of the back of the sofa making (or nearly making) a 90-degree bend. Your head should be hanging off the edge of the seat-cushions. The blood-flow to the head seems to instantly start to take it away. I have an ottoman to rest my head on. If you do not have one of these you can use the sofa cushions by stacking them up to right under your head for support. Try to make it that your head is slightly lower than the rest of your body. Do what feels comfortable to you. Stay there for however long you need.
Be careful coming back up. After an anxiety attack, especially, you will feel light-headed. Be sure to move very slowly and lay flat with your eyes closed for a minute or more before trying to get back up.
This does it for me. It is not a cure-all by any means but if I get a bad attack I do this after I start my breathing. For some reason bringing the feet and legs above your heart makes a huge difference.
This little ritual also helps if you feel one start to come on. You can lie on the floor and lift your legs up to a 90-degree bend and cross your feet. This should help keep it at bay.
Try it and let me know how it helped you all.
I do not take medications for my anxiety. I am leaving that for my last resort.