I average getting a cold about once every 10 years. I spend several hours a day outdoors (in all weather), come in contact with many people in public places and never even take aspirin.
Frankly, I think the body needs regular exposure to germs in order to keep the immune system in good shape. People that go out of their way to avoid germs end up getting sick more often because their immune systems aren't maintained in good shape.
For more proof of my theory, consider two public figures who obsessed over avoiding germs - Howard Hughes and Michael Jackson. Both of these people led sad, pathetic lives and were not in good health at all.
Now that's not to say that we shouldn't worry about hygiene at all but obsessing over it is no solution either.
My daughters have always gotten lots of colds. They almost died of a respiratory virus when they were babies.
One of my daughters has bad asthma with colds/flu. She’s out for about 2 weeks with a cold due to the asthma. She is a hand-sanitizer advocate. Last year, she was getting teased about washing her hands so much. She’d put up with the teasing, and still washed her hands.
I think the ones that do get sick a lot are the ones that wash their hands a lot. They know they are susceptible, so they are doing what they can to avoid getting sick.