One of the cardinal rules of Software Carpentry is never say 'just', because it signals the listener that the speaker thinks their problem is trivial. I've been reminded of this recently when hearing people say things like, "It doesn't matter what language you choose: just pick one and master it," or, "It doesn't matter what you build when you're first learning to program: just dive in and build something." Each time, I remember being at my first high school dance: "Just get out there and bop around" might have sounded like sensible advice to my exasperated friends, but they were a lot more coordinated than I was, and (demonstrably) a lot less worried about making themselves look ridiculous1. I had the same feeling twenty years later when I first started playing jazz. My teacher said, quite sincerely, "Just play something—anything," and was genuinely puzzled when I said, "But I don't know what to do."
My favorite talk at Ed Foo this year was by AnnMarie Thomas, who said, "Please stop telling people to fail fast and fail often, because only the privileged can afford to." More and more I feel the same way about "just try something", because a lot of people have learned the hard way that there's a cost to trying and failing, even if it's just the opportunity cost of things left undone. Making mistakes and recapitulating the thoughts of others are important parts of learning, but people shouldn't be shut out just because they don't want to wander around in the dark, bashing their shins against coffee tables, when someone could just turn on the goddamned lights.
 There are still two rules in our household: (1) Daddy doesn't dance. (2) Ever.