A mental habit I've been cultivating for several months with considerable success: "cardinality reduction".

I often find myself in a state where I'm keen to get things done, but there's no obvious next task to work on, and I don't have any specific desire to direct my attention. Bad things can happen in this state. I can start projects (initiate a git repo, open a book, start writing something, etc.), only to discover that I'm not in the mood for that particular type of task, before casting it aside, (perhaps developing an aversion to it in the process), and looking for another potentially abortive task. I can waste a lot of time casting around for the "right" thing to do, after which I feel like I've expended a lot of energy but have nothing to show for it.

Anyway, I've learned to recognise this state, and when it happens I tell myself "just reduce the cardinality of the total set of things that need to be done at some point", (i.e. "find something that needs doing, and do it"). This usually starts out as shallow maintenance tasks, chores, housework, etc., but with some frequency will turn into some complex dependent task lurking at the back of my to-do list. Something gets done, even if it's not what I might have imagined I'd end up doing, and I get my productivity afterglow rather than being frustrated at having wasted an evening not doing very much at all.

"Cardinality reduction" has become such a crystallised concept that I will sometimes schedule an hour of it, safe in the knowledge that afterwards, some progress will have been made on my assorted stuff.