Hi Kitty. I know exactly how you feel. I had to do some deep digging about what was really causing all my health fears, and bottom line I am terrified of dying, especially suddenly (you'd think I'd be more affraid of a long painful death). Anyhow, once I came to grips with that, I started asking myself what was really scaring me about death. For each thing that was scaring me about death, I decided on a tangible and immediate course of action I could take to make me feel a bit more at ease with this inevitable fact of life.
For example, one big thing was not seeing my kids grow up and having them know and remember me. So I started s c r a p b o o k i n g (have to type it like that or it stars out the curse word in the middle!!) with lots of family photos and journalling and letters to my kids and poems I wanted them to read and things about life I wanted them to know. Basically things I was affraid I might not have the chance to say to them. I also was affraid that some things that are important to me wouldn't be done when I was gone, like my kids education funds being kept up and them continuing to go to our church, and I wanted my best friend to have a close relationship with him, so I made a list of these things as well as some important loving words and put them in a letter for my husband, to be opened if I were to die. I also got more involved in my church, and reconnected with my faith, which gave me a lot of strength. And then I started identifying the things that I wasn't doing because of my fear, like not working in a field that I really wanted to be in, not spending enough time with my kids because I work full time, etc. And so I'm looking for a more fulfilling job with less hours.
Anyhow, those are just examples specific to my situation, but I can honestly say that they put my mind at ease a fair bit - they didn't take away all my fear, but they did reduce it a lot. I also joined a local CBT group which is going to help me retrain my brain to think in less catastrophic and fear-oriented patterns.
I've also heard that you are supposed to imagine the worst death possible over and over and over and over until you're so sick of it it doesn't scare you anymore. I haven't had the courage for that yet, but if anyone has done it and it worked, I'd