I am beginning to suspect that it is surprisingly common for intelligent, competent adults to somehow make it through the world for a few decades while missing some ordinary skill, like mailing a physical letter, folding a fitted sheet, depositing a check, or reading a bus schedule. Since these tasks are often presented atomically - or, worse, embedded implicitly into other instructions - and it is often possible to get around the need for them, this ignorance is not self-correcting. One can Google "how to deposit a check" and similar phrases, but the sorts of instructions that crop up are often misleading, rely on entangled and potentially similarly-deficient knowledge to be understandable, or are not so much instructions as they are tips and tricks and warnings for people who already know the basic procedure. Asking other people is more effective because they can respond to requests for clarification (and physically pointing at stuff is useful too), but embarrassing, since lacking these skills as an adult is stigmatized. (They are rarely even considered skills by people who have had them for a while.)
This seems like a bad situation. And - if I am correct and gaps like these are common - then it is something of a collective action problem to handle gap-filling without undue social drama. Supposedly, we're good at collective action problems, us rationalists, right? So I propose a thread for the purpose here, with the stipulation that all replies to gap announcements are to be constructive attempts at conveying the relevant procedural knowledge. No asking "how did you manage to be X years old without knowing that?" - if the gap-haver wishes to volunteer the information, that is fine, but asking is to be considered poor form.
(And yes, I have one. It's this: how in the world do people go about the supposedly atomic action of investing in the stock market? Here I am, sitting at my computer, and suppose I want a share of Apple - there isn't a button that says "Buy Our Stock" on their website. There goes my one idea. Where do I go and what do I do there?)
This suggests a different procedural knowledge gap: how do you tell when exercise is having an effect? Stepping on a scale doesn't give much information, since in the ideal case you're losing fat but replacing it with muscle. Counting weight and reps requires a reproducible routine, which I don't have, and only works for strength training anyways. I tried measuring endurance as "minutes on a treadmill at 6mph", but while there was a detectable upward trend it was nearly drowned out by day-to-day variance.
A good quick-and-dirty test uses the humble push-up. Periodically (every two or three days) just do as many push-ups as you can -- this will likely involve moderate discomfort on the last few -- and track the number you do over time. While there is some day to day variance, I think this is a pretty good rough proxy for general fitness and a few weeks of data would give you decent tracking of the trend, unless you are already in such good shape that marginal improvements are hard to discern.