This is the kind of writing where you write simply for the act of it. The page is not the destination; the writing is. In note-taking terms, fleeting notes belong to this kind. You write to engage — to get your mind to participate with the words on the paper or screen right in front of your eyes. The point is presence, not the artifact. Doodling and sketching serve the same purpose; what matters is that some part of you is actively reaching toward the thought rather than passively letting it drift by.
The more physical the activity, the better. Pen and paper are excellent, because the hand’s effort pulls the attention along with it. I like drawing the words on screen with a tablet — it is immediately available, and the physical engagement feels nearly on par. The body doing something concrete is what keeps the mind from wandering off mid-thought.
Starting one of these one-off notes should feel frictionless, with the tools always within reach; any hesitation defeats the purpose. And they are not for permanent storage. Process them regularly — extract the todos, file what deserves filing — then throw them out. Treating them as disposable is exactly what frees you to write without overthinking. (A practice I picked up from a note from a friend.)