The one item I'm missing here, and that is crucial before applying the other (great) tips is:
Learn to know and accept yourself.

You need to accept that you will panic and you will rush in, before you can coop with these behaviours.
If you are in denial ('I never panic') you will fall hard. First on the whole panicking, closely followed by a feeling of failure ('How did that happen?')

If you know what triggers your panic, you can find and train coping mechanisms.

Just my two cents...