Anxiety is the pits! I had that at first and it drove me crazy. I was afraid of this and afraid of that. The doctor had me on a lot of Valium and that was changing my personality, too. That's no way to live. Then I discovered that anxiety is basically fear so I asked myself what I was afraid of. I wasn't going to die from this illness. I'm a pretty strong person and I have a good head on my shoulders. I've been able to handle things that life has thrown at me before so why not this?!! (This is the reason for the quote in my signature.)
I now know when anxiety starts rearing it's ugly head and know I can handle it. I pretty much dismiss it because I know the racing heart, the weakness, shortness of breath, etc. is anxiety and not something that will kill me. It's just lousy anxiety! I get busy and start focusing on something else and sure enough those symptoms go away. The anxiety and the stress that it causes can cause more pain in fibromites. I don't need anymore pain. I have plenty, thank you! 
So I don't entertain anxiety like I used to .
Keeping a positive attitude helps immensely, too. I don't look at all my health issues and I do have plenty. Instead, I like to look at my blessings. I don't think about how I'm feeling. Instead I look at the plans and goals I made for the day and try to reach them. This helps me so much and I give myself a big pat on the back for any accomplishments that I make daily. That makes me feel good. I don't beat myself up for things I have problems doing. I usually can find a way to work around the fibro to do the things I need to do and want to do.
Lastly, I do have a good sense of humor. You need it with this illness...especially with the fibro fog! Yikes! Some of the crazy things we do can be alarming but, again, it won't kill you so it's better to laugh about it than stress over it. Stressing won't change a thing except the intensity of your pain. Yes, laughter is the best medicine!
So, all of the above is my version of "medicine" to help me get through each day. And you know what? The only side affects are happiness and hope for the future. I've had a good life in spite of fibro by using these techniques and also finding what takes the edge off my pain. I hope this helps all of you some.
Sherrine