Early this year a full-on panic attack hit me. The first time in 10 years. A recent divorce and changing jobs were probably the stressors. And ironically I was actually in a very happy place in my life. The divorce had been done with for several months and I was at a job where I can really have an impact and don't feel like I needed to look over my shoulder constantly. My boss's incredible understanding during this difficult time for me is testament to that.
But the panic doesn't much care about those things. It has a sneaky ability to strike when you least expect it.
Thankfully I found a great doctor whose therapy is evidence based. If you suffer from panic/anxiety and seek treatment (which I HIGHLY suggest you do!) then be sure they're trained in an evidence based technique. I also recommend reading "Hope And Help For Your Nerves" or listening to "Pass Through Panic" by Claire Weekes.
What I've learned in the months since is that in order to overcome the panic and anxiety you have to do something very simple yet seemingly incredibly difficult; you have to let it happen. Let the panic wash over you. Don't run. Don't distract yourself. Close your eyes and focus on breathing from your belly--deep breaths from the belly rather than shallow breaths from the chest. And then pay attention to where the panic is and what it feels like. Just observe whats happening and let it happen.
You have an upper-boundary to how bad it can get because your body can only produce so much adrenaline. So let it. It'll spend itself out and calm down automatically. The more you let it happen the faster you'll calm down because you're reworking those neural pathways. Literally retraining your brain that no, in fact, you're not being attacked by a lion. You might feel like you just got hit by a car afterwards and, interestingly, to your body its the same thing, but the significant bit here is you're not going to die!. You're not going to go crazy[1]!. You're going to be ok.
This time it might be a 10 on a scale of 1-10 but the next time, as long as you let it happen, it'll probably be an 8/9. Then the next time maybe a 5/6. And on and on until pretty soon it'll happen and you'll say, "Oh, hello old friend. Shall we do some work?"
[1]: "Going crazy" as a loose term for something like schizophrenia which the science is showing you will have a genetic predisposition towards. If you don't have a direct blood family member who suffers from it then you probably don't have it either.
EDIT: For clarification; I had stopped taking the medication a little over a year prior that first-in-10-years panic attack.