All of these methods could work, and probably do. It depends on the individual and what works best for you.
I have found that many things happen to me, when having a panic attack and most of the time I can stop it before it gets to bad. Usually I feel like I can't breathe, start to get dizzy and then comes the feeling of disassociation(or not being here). It literally feels like you are dying.
The trick, is to train yourself to use a method and practice it, then when the attack comes it will work as a second nature, and your attack will calm down faster and faster.
I have used the mantra and the deep breathing, sometimes one works best and sometimes the other, it depends on the situation.
The main thing is that it works.
Try one, then practice it, and when you have an attack you may find that it works. Maybe not right away, but with some time, it will work quicker.
Today will be a good day!
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