Some medical problems mimic/cause anxiety symptoms like how sleep problems can cause many mental problems.

A recent study showed a correlation between people with anxiety problems and higher than normal levels of CO2 in people's blood.Such as people who smoke, that have lung disease, or COPD.They thought the mechanism at play was an adaptive evolutionary repsonse to the feeling of drowning = feeling panic. For drowning & choking people CO2 increases quickly & panic sets in.

I imagine thats 1 way slow/deep breaths help calm people. It increased O2,& reduces CO2. I mention study to show how a physical problem not usually associated with anxiety can cause psych symptoms.

In the hospital patients with terminal lung disease often have panic attacks, despite not being low on O2.  In such cases antianxiety meds prevent or reduce symptoms but obviously do not fix underlying lung disease.

If opposed/reluctant to try meds, then find a midfullness practice you enjoy that uses breathing, like yoga or meditation , then practice it daily for at least 60 days, or for at least 60 sessions BEFOR you evaluate if your symptoms improved. You may be surprised at results. Dietary changes may also help. I saw PBS special from Dr Amen a neurobilogist that suggested certain changes in dietary protein vs carbs can affect certain brain types differently. See book change your brain change your life. Also maybe look into B complex vitamins or dietary sources of B vitamins.

I had a lot of anxiety growing up. I didn't even realize it was not normal to have that ball in my stomach all the time until I was 19 and went to counseling. You have to figure out what works for you, but the way I describe what I did was focus on getting rid of it. I put energy and effort into not worrying, into making myself relax and let go of the worries, reminding myself why it would all be okay and why I should NOT worry. Usually whatever you put effort into is what you feel - so if you put effort into feeling relaxed you will relax, if you put effort into worrying you will feel anxious.

I was a very nervous kid, I would freak out when my Mother crossed the street, fearing something terrible would happen. She told me to stop sending "negative vibes into the atmosphere" like that. Silly, maybe. But repeating that mantra has helped me for years.

Recognize that those worry thoughts are just "monkey mind." Have you tried a cognitive behavioral approach? My anxiety can sometimes have a snowball effect, so when I feel anxious I try to stop the cycle then and there. At night, try some muscle relaxation as well. Tense for 10 seconds, release for 10 slowly - from head to toe. Works for me!

This may sound overly simple, but my best advice is to "just breathe." You may think "well, duh, I'm already doing that... I always breathe" but I mean taking slow, deep, controlled breaths, focussing on nothing but the breathing pattern and the different motions and body parts involved in the breathing. Sounds simple, but it does a lot of helpful things. It slows down your heart rate. It helps you get needed oxygen to your brain (anxiety often causes us to take shallow, weak breaths, which combined with a racing heart can simply knock us out). Slowing down and focussing on breathing also helps you get out of the "Fight or flight" mentality that is the cause of anxiety and panic attacks. It's very hard to be fight-or-flight when you're sitting still and thinking of nothing but your breath.

It also helps immensely to, once you've calmed your heart rate and breathing, take a mental step back and try to take in a big picture view of the thing you're worrying about. Often times you can see that it's really not worth the effort exerted in worrying about it.

Most importantly, eliminate the following questions from you life... "What if...?" Nothing would get me into a panic attack faster than "What if"-ing. There are a lot of things in life we can't prepare for, and worrying about them gets us nowhere! So breathe! :)