First cold I've had in AGES,

[PoindexterOglethorpe]

14. There are a limited number of cold viruses out there.

I've seen various numbers, but a quick Google search told me 200. And here's what you need to understand. You get a cold. You recover. You are now permanently immune to that specific virus. 199 left. You get another cold. You recover. You are now permanently immune to that specific virus. 198 left.

Get the pattern?

In youth, it is common to get a cold two or four times a year, sometimes more if you're unlucky. That usually lasts into your thirties. Eventually, you are exposed to all or nearly all of the 200 cold viruses. Eventually, you stop getting colds.

Speaking from personal experience, I got my share of colds from childhood and through my 30s. Since then, I've rarely gotten a cold, and in the last two decades (I'm now 71) I get less than one cold a year. Hooray for getting old!

Oh, and in a related comment, I don't get the flu. Nor do I bother with the flu shot. I got flu several times in my childhood, including the Asian flu in 1957. I figure my flu immunity is as strong as it can get.