I had random panic attacks briefly in my early 20s, probably was resultant of lifestyle: too much caffeine all nighters studying, stress, drinking/partying etc.
IN addition to what was mentioned, which is more important and effective, try to train your mind to stop thinking. By that I mean, once you start thinking about something, don't dwell on it and continue down the path: like say for example, when you get angry at something, then the more you think about whatever it was the angrier you get, accomplishing nothnig bet getting angrier which has physiological consequence, just stop as soon as the anxiety starts...think or do something else, like something challenging that requires your full attention and is intereisting, recognizing that it takes time and practice to get better. Before you know it maybe you'll be in full control of your mind, instead of your mind controlling you.
Your anxiety also might be telling you something is wrong, that there is something knowingly or uknowingly you need to be wroking on or fixing. One time I was boarded on a plane and my heart just started racing, prolly 180 bpm out of nowhere, then I noticed a wierd smell, calmed myself down thinking,"surely that's just in my mind, my anxiety!" so I stopped thinking about it and instead the miracle of aviation and how safe it is. A fe minutes later the captain came on the intercom that we were going to deboard the plane due to the strange smell.