I meditate regularly, but I think this type of exercise is misguided and betrays the body-denying/denigrating bias that can be often found in religious traditions world-wide. It encourages an ignorant attitude towards the body: instead of contemplating the miracles of the muscular system, see it as amorphous flesh. Amplify the spurious association of the skeleton with the malnourished body it resembles, instead of marveling at the ingenious way it serves it's (many) purposes, and so on.
I generally agree with you that a lot of lineages, particularly the Theravada derived ones here in the west, might go overboard with body denial practices. The meditations from the Satipatthana sutra are great, but I feel like you can get caught in trying to prove everything is suffering if you don’t have enough grounding in other parts of Buddhist teachings because of them. Like all of the sutras it can point you in a direction, but we shouldn’t be caught up in them.
Personally, in my meditation practice, it was completely transformed and deepened when I began a dedicated asana practice and focused on giving my body what it needs to be strong and in touch with what it is saying.
That's like saying you are not your car; while you're driving the distinction is less important than keeping between the lines and watching for pedestrians.
I am a Daoist like everyone else is a Gravitist. You all believe gravity because you feel it work and it was explained and named to you. You feel Daoism and Buddhism work as well but no one has explained to to you.
… I don't know how to respond. Mu, I guess? As I see it, you are mixing several senses of the word "to be", and the resulting question is meaningless.
The pattern of my mind is physically instantiated (as all the ten thousand things are), and it happens to be so instantiated on a brain. That brain is housed in a body. The pattern can direct the shape and properties of the body only to a limited extent: there are heavy restrictions which happen to constrain the power that pattern (or rather, its particular instantiation on this particular brain) has over the body. (We call these restrictions "biology".) I could no more order my body to become immortal than I could order the ocean waves to stand still: they are both governed by the same laws of physics over which I have almost no control. I could probably make my body immortal by some sufficiently clever manipulation of the world (possibly involving waves hands wildly nanobots), but the brain did not come pre-packaged with high-fidelity fine-grained control over its environment; the pattern can interact with the world only by flapping around bits of meat, and these are a very blunt instrument, highly unsuitable for difficult tasks like "reverse entropy in this region of space".
