first of all sit calmly and take a deeep breath hold it for 3 seconds then slowly release the breath through your mouth.. and you have to accept the fact that its a panic attack which is eventualy gonna pass.. whenever you have attacks or feel like you are gonna have it just look around your self and name the first 3 things you see then hear and name the 3 things you hear from your enviroment then go.towards the mirror and look at your self eye to eye and smile and talk to yourself and challenge the anxiety by saying things like you cant beat me/i am so much stronger than you.. and once your brain has accepted the fact that you have overcome the anxiety or depression and came to know its just your brain playing games with you to scare you it will decrease day by day
