I read a technique that's really helped me, I think a lot my anxiety problems came from negative thoughts and images coming in my head unbidden. I read that these thoughts are perfectly normal (seems obvious now!),but you have the option whether to engage with them or not, and that's where one of my problems were, I would engage with them and turn them over and over and inside out and, then, start the whole process all over again.
So the technique was to think of these thoughts/images, as they came in and out of your head, as a film reel passing in front of you; each image on the reel being a thought or image. The idea is to only stop and focus on the positive images (thoughts),allowing the negative ones to pass you by. An alternative was to think of them as a train, and as you stood at a train station, allow negative thoughts to come in and pass on through, without stopping.
This really helped me. For one it stopped me trying to prevent the negative thoughts, that were causing me so much distress, from entering my head... a losing battle! But it also (slowly but surely, it wasn't a quick fix!) helped me stop dwelling on and remunerating on the thoughts that caused my anxiety and panic attacks.