I used to get anxiety attacks in crowded public places when I was younger. People told me they could never tell I was having one because I was so good at covering it up. Covering it up may make everything look fine and dandy to those around you, but it sure sucks keeping it in. What it took for me to get over having panick attacks (haven't had one in years), was
negative self-talk. Granted, not everyone has the same outlook on life as I do, but adopting my outlook on life during a panick attack might just work.
Here's what you do. Keep in mind, that this applies to not only panick attacks, but general anxiety as well, be it in a public place, or in your living room when you know you have a meeting in a few hours, etc. Hell, if someone is pissing you the fuck off, and you really want to run them over with your car, it'll work there too. Tell yourself, and don't hold back one bit, that life is pointless. We're born, we live a tough life where most of us have to live paycheck to paycheck, never achieving dreams or really truely living, and then we die.
The earth we live on is a fucking spec in a massive universe, hell, there could be more than one universe, there could be infinite universes. Do you really think anything you ever do will matter? Do you really think anyone will ever remember you, or care that you existed? Everything man does, even those who cure diseases, is pointless, a waste of time. In the entire span of the universe's life time, our planet somehow spawned us. Our planet, and by comparison, our lives, are a spec. Our planet is nice and old, so by comparison, our lives are a millisecond long. Nothing you or I do will ever matter. Your neighbour doesn't matter, your best friend doesn't matter. If you rolled over and died, only the people who know you would care. What is 1 life on a planet of 6 billion people?
If you die in a car accident tommorow, no one will ever remember you. No one will ever care you existed. If someone dies in a car accident tommorow, you won't remember them or care that they died. Human beings are animals, albeit, animals that're arrogant enough to believe they were created by some higher being. As long as you remember that nothing you do will ever matter, that your life is pointless, with no meaning, with no reason behind it, you're invincible. People who spend their time worrying about things are throwing away time they could have used to have fun. Why worry about the meeting in a few hours when you're going to be meeting some friends for lunch?
Think everyone is looking at you? That you somehow stand out? You probably don't, but even if you did, who cares? Great, they're looking at you, and then when you leave their field of vision, they'll forget you ever existed. If you get hit by a car 5 minutes later and end up imbedded in a concrete wall 100 yards away, they wont care. Likewise, if the same happens to them, you won't care either.
Life is pointless, and so are you, so why worry, why panick? What's it going to accomplish? Nothing, just like you. It's impossible to accomplish anything when you have no reason to exist. Mankind has no reason to exist. Never has, never will, but since we're here, whether we like it or not, we have to make the best of this shitfest we were born into.
So basically, that's what I did/do whenever I feel anxiety or panick attacks coming on. It's pointless to panick about something that will never matter, or something that no one will remember or give a shit about. Even if there is other life out there in the universe somewhere, they wont care. By comparison, their existence is just as feeble and meaningless as ours. Even if they know you, personally, exist, they still wont care.
As long as I maintain 100% nihilistic thoughts during anxiety or panick attacks, I can keep them at bay and be perfectly fine
