When you have anxiety attacks, you have to talk to yourself and learn how to calm yourself down.
The first thing that you tell yourself is that it is only a feeling. There is nothing physically wrong with you and you will get through it. Do not entertain negative or frightening thoughts. Shift your thoughts to something that you really like, such as walking in the woods or sitting on a beach. Begin to concentrate on that subject and picture the beautiful scenery in your mind. As you do this, breath naturally and slowly. If you feel tension, relax each limb and let the tension go.

To avoid anxiety attacks in the future, eat a balanced diet with lots of fruits and vegetables. Stay away from caffeine and alcohol. Start an exercise program. Stay connected with friends and family members. If there is anything that is bothering you, talk to someone about it and do not hold it in.
All of these things will relieve stress.

I can tell you what has always worked for me. The most important part of this answer, though, is that it's only going to work if you recognize right away that you're feeling an irrational sense of panic or anxiety. The first thing to do, if possible, is to remove yourself from the situation and concentrate only on what you are feeling. Realize that the first thing you need is oxygen. Concentrate as deeply as you can on breathing in - slowly - and breathing out - slowly. Continue to do this until you feel like you're able to rationally process your thoughts again.

What anxiety/panic do is to convince our brains and bodies that we have lost control, but this is not the case. It is possible to stop an attack in its tracks if you recognize it coming on.

If it comes on rapidly or without warning, try to turn on a tape in your head that repeats that you are safe. Say something to yourself repeatedly such as, "I am safe. I am in no danger. There is no need for me to fight. There is no need for me to flee. I am rational and can handle the situation before me."

On a daily basis, try to engage in something that relaxes you - walking, writing, journaling - and encourage yourself to spend at least five minutes a day doing some sort of deep breathing and stretching.

Focusing on the importance of sustaining your body through breathing is a must.

:-) Good luck to you!

Meditation works well for reducing anxiety. It is like the opposite of stress. Most of the long list of health benefits you get when doing meditation are because it reduces stress. When you meditate you learn how to become deeply relaxed. With practice you can learn to relax at will.

You may need some help to meditate. I can meditate more deeply if I use meditation programs that alter my brain waves. If you do a search you should be able to find some good ones. A lot of them offer free samples.