I and many others have benefited a lot from learning how to breathe deep and slow, in a relaxed way.
most anxiety sufferers breathe too fast, taking shallow breaths
this can be pleasant and distracting short term but increases the anxiety long term and may bring on a panic attack, the balance of gasses in the system can become wrong, also some of the same air goes up and down the windpipe
I originally couldnt take a deep breath, my chest expansion was judged poor by doctors, I expect from cronic muscle tension from my anxiety
I then did a SCUBA diving course, which requires deep slow breaths to make best use of the air. shortly after I was told of the benefits from deep slow breathing and it was easier for me to do it
when relaxed, I now breathe 5 times a minute, much slower than the normal rate of 15 to 20 times a minute
(in and out being counted as one breath)
I should find out whether this is considered safe or OK, I guess
remember when doing this breathing, you need to relax your muscles as much as you can, the stomach and the lungs get bigger together as you breathe in, and both get smaller as you breathe out
fill your lungs with air then let it flow out, dont force things. you will probably feel dizzy at first due to the extra oxygen but you will soon get used to it
also dont forget to breathe when concentrating hard on something