Security and hairdressing
I've become an amateur hairdresser in the past couple of years, thanks to my three year old (I suspect that, had I been unwilling to do so, her hair would be quite short right now). Along the way, I've realized that I know as much about hairdressing as I do about many of the disciplines InfoSec touches.
For those of you who've never braided hair, let's try a little manual experiment. Go get three strings. Tie them together at one end to a fixed object: maybe a railing. Now braid them: holding them extended, switch the middle and right one; then the (new) middle and left one. Repeat, each time making sure the middle one goes under the outer one. Do this a couple of times, until you're comfortable with it.
You now know as much about hairstyling as you probably know about some of the more esoteric security disciplines: executive extraction, availability analysis, crypto design, or fault isolation in Byzantine networks. You haven't had to deal with snarls, or working with multiple different hair types, or tried a French braid. Similarly, you may never have designed a communications protocol, or walked a perimeter, or managed IDS sensors on the other end of an intercontinental straw.
Yet every day, as infosec professionals, we are compelled to guide other professionals in how to do their jobs. My advice: be a bit humble. As smart and clever as we think we are, the professionals we deal with are smarter in their own disciplines.