The Circle of Skill Issue
There's a concept in psychology of "Circles of Concern, Influence, and Control"
Your Circle of Concern is everything you care about, including things you can't necessarily affect, like the weather. Within that is your Circle of Influence, containing stuff you can affect but not control, like whether you get promoted at work. Within that, your Circle of Control is stuff you have full control over, like what words you say.
Importantly, the exact boundaries of the circle of control are fuzzy, movable, and usually not quite where people think they are. In particular, I like to imagine a circle that surrounds the circle of control, that I'll call "The Circle of Skill Issue". This contains things which seem like you can only influence them, or like you can't affect them at all, but which you actually could fully control, if you knew how.
Consider this newborn baby
This baby's circle of control is tiny, and doesn't contain things like basic bodily functions, or the movement of her limbs. But the thing is, her nerves are connected up the same as yours and mine - in a sense her body is already "fully under her control", she just hasn't learned how to control it yet.
This continues into adulthood. Some people can roll their tongues and some can't, some can waggle their ears or flare their nostrils and some can't. Importantly, the boundaries here are not obvious. Being unable to roll your tongue feels the same as being unable to waggle your ears - you try to make the muscle do the thing, and it doesn't work. But tongue rolling is genetic - many people will never be able to do it, it's forever outside of their circle of control, or even their circle of influence. Whereas basically anyone can learn ear waggling or nostril flaring, those are both just flexing specific muscles. If you can't control your ears and nostrils, it's not because they're literally outside your control - the nerves are all hooked up, the muscles are 'under your control', you just haven't learned how to use them yet. Such things are in your Circle of Skill Issue. These are things you can learn, and thereby move into your Circle of Control.
Learning to do this kind of thing usually looks like either spamming random muscle movement signals in the right general area and noticing if any of them cause your ears to move, or doing some conscious motion that includes moving the target muscles as a component, like smiling or raising your eyebrows, and then isolating the specific muscle from that. By carefully focusing on what mental motions cause which muscles to move, and practicing a bunch, you can steadily build up full deliberate control over these muscles.
I'm not saying you should do this for its own sake, to be clear - the reason you never learned how to use these muscles is because it's basically never useful to use them.
But the thing is, these kinds of things can be self-fulfilling prophecies. Practically speaking, you can't learn how to waggle your ears unless you believe that ear waggling can be learned. If you believe it's outside your control, you're automatically correct.
This isn't hypothetical, because... I kind of lied before, tongue rolling is not purely genetic! A study found that for 7 out of 33 pairs of identical twins, one twin could roll their tongue and the other couldn't. This suggests that there are currently large numbers of people in the world who learned in school that tongue rolling was genetic, tried to do it once and couldn't, and then never tried again, even though they could learn if they tried!
Tongue rolling isn't important, but consider the broader implications! You probably currently have things which are fully in your control, but which you think of as fully outside of it! Some of them might be very important!
If our culture holds that something is outside of our control, we don't have a reason to try to learn how to control it, so we can't tell whether its controllable or not.
Some things that we are told are outside of our control but sometimes might not be:
Taste in food - I already know this one is controllable because I've learned how to do it, and now there are basically no foods I dislike
Emotions - I've never felt emotions very strongly so I can't tell whether I'm good at controlling them, or whether I just don't have much to control. Or, for that matter, whether those might be two sides of the same coin
Hiccups/Coughing/Sneezing? - I've definitely just Decided Not To Have Hiccups Any More and had that work
This is all very low confidence, and can of course veer dangerously close to unhelpful and harmful sentiments that amount to "have you tried being normal?", which is not at all what I mean. Many things are in fact totally outside of your control, and the last thing I want to do is encourage people to give themselves a hard time about things they can't change. If you read this and think some variation on "Ah, as I suspected, my problems are all just caused by me being Bad and just Not Trying Hard Enough", then The Law of Equal and Opposite Advice is hitting you really hard and you likely need to move in the opposite direction.
But like, have you actually tried though?
If you don't know how to waggle your ears, flare your nostrils, or roll your tongue, I recommend you try learning it. (Or, if you know all of those, then learn crossing your eyes at will, or going wall-eyed at will, or de-focusing your vision at will, etc). Not because these are useful things to learn in their own right, but because it's useful to learn (or I guess to remind yourself) what it feels like to learn to control something that you previously had no control over.
If you can do that, I do think it's worth experimenting with applying the same general types of mental motions - the moves which would allow you to learn how to waggle your ears - to all kinds of other things that you probably don't have control over, just to see. Just take some time to consider, like "If I assume for a minute that this thing is actually fully under my control, and I just don't know how to work it yet, what would I need to do in order to figure it out?". Maybe you can spam all kinds of random possibly-related mental motions/commands and see if any of them affect it. Or, the next time the thing you want to do 'just happens' or happens by accident, introspect carefully on the experience, and see if you can reproduce any of the mental motions that feel connected to it.
You may have control over more than you realise.