Hey nurseboy...I can also get used to my anxiety. For me, the most difficult time is when I've been free of it for a while, and then it comes back (due to not practising breathing, visualization, relaxation, etc.). Once the anxiety has been around for a bit, I usually develop coping methods...and it starts to clear up.
Like you, I also "panic" when I don't have anxiety!! I think we get so used to feeling bad, that we seek to hit that level. I found self-talk was a good help with this. It takes a while, but I found that when I wrote up a list of positive statements that I'd review throughout the day, it eventually had an impact.
