Hi Paul,
I also suffer from health anxiety, so I know how the worry feels about having ill health. Living more healthily may make you feel better not only by cutting your risk but also by giving you more energy. It's not a guaranteed cure however as I live very healthily and still worry about my health, but you may find being more active at least puts some good energy into your life!
If it is specifically heart trouble, clots etc, you could look at how your diet may help, you may find that this alleviates your anxiety a little. let us know how you get on!