Woody Allen pens a great (and hilarious!) piece about hypochondria: 

But why should I live in such constant terror? I take great care of myself. I have a personal trainer who has me up to 50 push-ups a month, and combined with my knee bends and situps, I can now press the 100-pound barbell over my head with only minimal tearing of my stomach wall. I never smoke and I watch what I eat, carefully avoiding any foods that give pleasure. (Basically, I adhere to the Mediterranean diet of olive oil, nuts, figs and goat cheese, and except for the occasional impulse to become a rug salesman, it works.) In addition to yearly physicals I get all available vaccines and inoculations, making me immune to everything from Whipple’s disease to the Andromeda strain.

Best line in the op-ed:

Even when the results of my yearly checkup show perfect health, how can I relax knowing that the minute I leave the doctor’s office something may start growing in me and, by the time a full year rolls around, my chest X-ray will look like a Jackson Pollock?

I, too, would classify myself as an alarmist. But an occasional one, not a full-time one like Woody Allen.