superstitious meditation, muscle tension, and will:

These are rhetorical or koan-ish sorts of questions (more phenomenological than mechanism-related, neuroscientific, causal, or even-ish teleological):

How do you move your body? Or how does your body move? Or if you can make your hands heat up or stop hiccuping or deliberately open up your nasal turbinates or stimulate intestinal peristalsis, how do you do that? Or, if you're a yogi(ni), how do you temporarily stop your heart (more like subtle atrial fibrillation, maybe, but anyway). What about entering nirodha samapatti or something? Or old research studies of people stimulating their immune system? Do you do these things "directly"? (and what does that mean?) Or "indirectly"? For example, if your breathing slows, that raises CO2, and that can cause your nasal turbinates to open up, and that's something that you can do deliberately/intentionally/consciously; or, you might not realize you're doing it, if you're "concentrating" or something. Or is, e.g. weight loss, when it works, "all technical," the right combination of macros, micros, timing, etc., and then it happens by itself; or is there a mental component, or both, and when is that a false dichotomy, and so on.

Anyway, what are all the ways you directly or indirectly cause (or not) something bodymind-related (or otherwise) to happen? Or the ways in which things just happen? (This is also rhetorical or koan-ish.):

There's, loosely speaking, with overlap and vagueness, intention, intending, will/volition, deliberate action, bottom-up action, spontaneous happening, "participation," intercessory prayer, asking the universe, doing magic, trigger-action plans, commanding yourself, and so on, and so on.

And, like, as a hypothetical, non-presupposing example, do you "momentarily" "intend," as an example, or do "you" "maintain" an "intention" in the "background" or "foreground" or does "something else" "take over" or do you "set it and forget it" or return intermittently or regularly to it, like ringing a bell, or something. And what about in the far reaches of meditation? Does the "intending self" sort of "eat itself with no remainder"? Or, what's "really going on"? And/or is that ineffable? And, aren't self, body, mind, bodymind, etc., empty in the technical sense? How does that all fit together?

The point of all the above is something like, over the course of our lives, we build up a lot of assumptions about how the bodymind moves and functions and acts upon itself, and so on. And, in meditation, those assumptions can be magnified or doubled-down-upon, before they're eventually corrected, and dimensions that persist longer, before they're corrected, can lead to things like muscle tension.

As an example, leaving aside the ethics of the original experiment, which I haven't thought through at the time of this writing, and, so the story goes, B.F. Skinner would have pigeons peck buttons that would light up in order to receive food. But, when the button lit up, it wouldn't always dispense food. So, the pigeons would sort of develop these elaborate behavioral dances, before, after, and between pecks, as, perhaps, they tried to figure out they connection between their behavior and how to get food to actually dispense. In some sense, arguably, the pigeons were acting "superstitiously." Here, that would be something like "acting erroneously or elaborately on the basis of incorrect or hopeful beliefs about the relationship between cause and effect."

So, a lot of human behavior, down to really subtle levels can be "superstitious," in some sense. Or, a lot of what we do, even when it does work, can have a lot of "extra" stuff that comes along with it, that can come before or after the thing that actually does the thing or concurrently. Or, the thing that actually does the thing can be really indirect and almost incidental with respect to how we're (trying) to produce the effect, consciously and unconsciously.

And a lot of what meditation is "raising" and working through all that superstition, including presupposed ontology, along with a lot of initial "error propagation" and "doubling down" and making things worse, sometimes a lot worse, along some pervasive and subtle dimensions, before those dimensions get better and better.

So, here's a simple, toy model:

Say, first-pass, you're composed of an (a) "I" and (b) a "me." Or (a) "self" and (b) "parts." Or something like that.

A lot of problems are caused by clashes or confusions between (a) and (b). Say that one is trying to take the other's jobs. Or one is trying to become infinitely or perfectly strong and to clobber or completely control or even erase the other. Or one believes it or the other is the only "true" one and that the other is an illusion. Or one or even something else is trying to "merge" the two or treat them the same. And so on. (You of course may find that interacting constructively with parts causes them to become less and less part-like and more and more integrated or that "I" and "me" do or don't eventually dissolve into awareness or centerlessness or agencylessness or something, or sensations can't directly affect other sensations, etc., etc., and/but empty isn't the same as illusory, and so on and so forth. In any case, models are useful for as long as they're somewhat phenomenologically resonant or usefully evocative.)

So, you might provisionally assume or play with the idea that there's an "I" and "me" or an "I" and "parts" or "self" and "parts," and so on.

And whether it's "I" interacting with "I" or "I" interacting with "parts" or "parts" interacting with "parts," or the world or univesre (cf. "asking the universe," cf. your current tacit or explicit beliefs about how the bodymind works or your cosmology and so on), you might distinguish between things like:

action,
will,
requesting,
imperatively "telling" or commanding,
spontaneous happening, and so on.

Or, more simply, are you "telling" or are you "asking"? And can the other part safely say "no"? Can you or the asking or telling part safely hear a "no"? And/or are you or the asking or telling part going to try to make it happen anyway? (cf. pushing and forcing and so on)

And if you/"I" can safely hear a "no," and the "me" or other part can safely say no, and there's not habitual "trying to make it happen, no matter what," then there's a possibility of dialogue or negotiation, which could be heavyweight and verbal (and one can always play with that, even in far reaches, for pockets of redo-to-undo or as a fluidly settled thing), and/but can get more and more liminally verbal, nonverbal and self-telepathic, subtler and subtler untanglings and refactorings and resortings and more and more and finally ever-always spontaneous. (And even this toy model is too reifying. The full space is something like all the auxiliary and main practices and beyond, not just "negotiation," but this is a potentially very helpful and useful toy (and actionable, depending on regime, loosely speaking) model.)

So, cf. global-wayfinding-aware and with respect to subtler and subtler tangles, are you being superstitious about voltionality or your capacity to directly cause? Say, are you confusing "I" with "me"?

Are you asking or telling? Who (or what) is asking or telling? And to whom (or what)?

Notes:

Why is "will" so prominent in main practice p2 if it's sort of so fraught and prone to misunderstanding? Won't people be more likely to double-down and error propagate on something superstitious in there? Possibly. This is somewhat empirical. A lot of people reify something like "will" and people might find and uncover their errors more quickly if it's front-and-center; and, also, sort of saying the same thing, it may put redo-to-undo up-front in service of that. But it depends on the reader/practioners interpretation, personal ordering, and so on. There are tradeoffs, and something else might be better.
cf. ineffable (without connotations of great or extreme, though)
doing vs doing vs telling vs asking /vs [sic] (general) receptivity // .."listening"