I might be flamed for this, but if you eat healthy (the REAL healthy, not what most of America considers healthy), exercise regularly, and take a multivitamin, then you don't even need to see a doctor unless you notice something seriously wrong. My personal experience with doctors is that they overprescribe medicine for something that can be easily prevented through the integration of healthy habits.
I used to get sick a lot with colds and what not, and my mother would make me an appointment to "check things out" and I would always get an antibiotic prescribed for me "in case it was an infection", and it would only end up making me feel drowsy for the next week or two. Now that I have adopted a healthy lifestyle, I've been sick once in one year and I got over it in three days. Also, a couple years ago I was prescribed Accutane for acne, and all it *seems* to have managed to do is mess with my hormones.. I think if the doctor would have just told me to stop drinking soda, stop eating fat-laden foods, and eating a clean diet, the acne would have just subsided on its own with the help of topical cleansers (which it has).
I'll step off of the soap box now.. I hope I'm not taking too radical of a viewpoint! It just bothers me when people say they have a very weak immune system when their diet consists of Skittles and potato chips. "You are what you eat" comes into mind.
This isn't to say you shouldn't have health insurance, what if you break your leg or get into a car accident?