When I was young, I used to love sitting in the bath as the water was draining out. I would feel the subtle change in weight as my body floated less and settled more. This experience was surreally solidifying! It felt (each and every time) as though my body were being re-constructed; build again; newly emerging from a static state of equilibrium.
This memory came to me as I bathed my son and recommended he try it... You would have thought I just taught him how to fly!!
His half-submerged, smiling face peered wide-eyed up at me as if to say, "This is awesome!!! Why haven't you shown me that yet!!!!???"
Now, he HAS to do it almost every bath...
If you are too "grown up" to try that again - and you aren't - there are other ways to explore the strange alterations of bodily-spacial (dis)equilibrium. For instance, if you have never tried laying on the floor while pretending to sink into it, I strongly recommend it!
Imagining your body blending into your immediate environment carries with it a sort of softly blissful sensation that can really be felt (with a gentle "hum") throughout the body. This sensation can also be discovered (to a somewhat unbelievable degree) in the practicing of watching the mind during silent mental skills practice (meditation). Surprisingly, it can be fairly simple to uncover. Simple, however, does not always mean easy...
To help find the "right effort" (the balance of "trying" and "doing nothing") while developing a skillful mind in such a way that requires dutiful concentration (such as holding focused attention on the breath) consider the following analogy:
Imagine you are sitting on a beach (I know, cliche... but where else can you find so much sand!!?). Feel the body lying against the warm, somehow silky-scratchy sanded earth. The gently cradling waves creep up your feet, ankles, legs, waist, torso, arms, shoulders, and neck; the water lifts itself subtly your head to brush against your ears. With each in-breath, feel the water tentatively crawl out of its immense depths to envelope the collective object you have known your whole life as "your body".
With each out-breath, notice the recession of the wave peeling off the skin like a warm blanket carrying with it infinitesimal amounts of sand... as if one grain at a time was being removed from underneath your resting pose.
As the repetitions of waves are noticed with clarity, feel your body sinking slightly. While being absorbed by the sunken spaces of the beach where you lay, also feel the breath being "absorbed" by the body. Struggle against it, and the spaces will quickly fill up again, leaving uncomfortable lumps of beach under your weight. But, release the urge to resist - in other words, give yourself over to the fleeting moments of breathing - and the ground will soon hollow itself back out to swaddle you in its dynamic surface.
Each cycle of the waves (in and out) brings a stronger sense of calm and comforting depth; like pouring yourself deeply into a loving hug. The waves are your breath; the sunken spaces are your refuge.
One wave at a time: Up... Down... Sinking... One breath at a time: In... Out... Sinking...
Soon, as the breaths become more and more subtle - not necessarily lighter, but more transparent and crystalline streams of air - the "you" that sat down to try to white-knukle it through another 30 minutes of arguably the most boring activity in the world can gradually discover a sense of wonder at the enjoyment of sitting and breathing.
Noticing, now and again, a sort of "blipping back in", the sense of self is now slightly more loosely bound. The solid bodily stuff of bones and flesh are now simply things there to notice. The typically-whirling mind of thought and feeling now appears more like a light drizzle of rain than a tyrannical tsunami. The familiar "me" has been not transformed, but seen from an angle revealing its fragility and compound nature. Even the very surface of reflective consciousness is held apart from the "self" - seen now as merely light refracting off the surface of water, not the ocean itself.
Abiding there in that peaceful "loss-of-me-ness" can be fantastic. A sweet, almost dull, but somehow-satisfying departure from normal perception. Watching yourself watch yourself; "seeing" the "seer" "see".
An interesting thing for me to explore, anyway. Try it and you may just find yourself wholly different than you ever thought...