As an adult, what happens if I never get flu shots, vaccinations, and or physicals?

At 34, and I guess besides exercising regularly, getting checked after sex, using common remedies to take care of colds or worse and without seeing the doctor, what are my risks even if I do all of these things myself? Now, I tan on an off and on basis seasonally, eat between healthy and non-healthy foods in moderation including plenty of fruits and vegetables, and I drink water everyday ... morning, noon, and night. I also take in alcohol but its pretty rare as I cannot stand beer but top-shelf and hard liquor is my favorite semi-moderate intake. Anyway, you get the idea. Oh, I forgot, what are your thoughts on multi-vitimins? I think they're full of crock.