I have the same thing. I'm a total hypochondriac. And unfortunately I have some minor (I hope!) health issues that make me uncomfortable regularly, so there's no shortage of physical discomfort to make my imagination go wild. I try to distract myself from my health anxiety with anything that can engage me--books, movies, work, music, etc. I also try to make myself as comfortable as possible, with hot showers, baths, lying in bed with a heating pad on my stomach, etc. One thing I find helps is gentle stretching, not following any routine, to music. I do it for as long as I feel like doing it--yoga poses like child's pose, cat/cow, cobra, side-to-side rocking with one arm extended. I like stretching my back out and just breathing. I treat this as me-time, not for the purpose of getting in shape or anything, but just connecting with my body. I try to tell myself that thinking about death is a bad habit and I need to gently move my attention to something else. Is there any activity that deeply engages you?