I don't get the flu vaccine. Don't get me wrong, I definitely value its use, and I have no political inclination not to get it. I just tend to get caught up in things that tend to be more relevant and stressful in the moment. Oops
I'm certainly not crazy about cleanliness either. I often eat with the same unwashed hands I just groomed my horse with. I hate hand sanitizer, I really do. I don't pay any more attention to hygiene while using public bathrooms than I would in my own home. I don't run away screaming from every person who sneezes. I don't spray/wipe down anything ever unless I need to at my job because I'm expected to.
Literally, the most effort I've ever put into not getting sick is "Well, that other student in class who touched my stuff is visibly sick, so maybe I shouldn't put my hands near my face for a while."
That being said, I rarely get sick *furiously knocking on wood*. The only time I got sick in the past four years was when I had some strange pounding headache for a couple days, but it didn't stop me from riding and working out. I don't even know if I was sick or if something else was off. When I do get sick, and it's been a very long time since I have, it's often a "Huh, I'm sort of sniffly, maybe I'm sick" and then the next day it's gone. I don't remember the last time I got sick with something more than that. I also don't remember the last time I vomited, for any reason.
Last semester my boyfriend was sick for a couple months straight. He went to the doctor and got tested, turns out it's the second time in his life he's gotten mono. I share a house, a bed, a bathroom, sometimes a car with him... Also wasn't afraid to kiss him then either. I never got sick.
Don't know what it is, honestly.