I found a freckle on my boyfriend's knee that he never even knew was there.
I was pretty gobsmacked by this. Not the freckle - it was a good freckle, but, well, freckles are freckles - but the idea that you could live for 23 years and not know every inch of your own body. Did he not spend his teenage years gazing into mirrors, wondering whether his eyebrows were too close together? Didn't he analyse his arse from every conceivable angle, employing complex arrangements of mirrors to ascertain whether both cheeks were actually the same size? Didn't he count every blemish, every imagined imperfection, and wonder just how hideous on a scale of grotesque to eyeball-meltingly horrifying they made him to other people? Did he honestly never think, "does this knee freckle make me look fat?"
Nope. Because he was an athlete, and, his whole life, his experience of his body was focused on what it could do, not what it looked like. He knows precisely how many sit ups he could do in one go when he was sixteen, but that freckle somehow escaped notice.
It seems like we're very extreme examples of how men and women - or teenage boys and teenage girls, anyway - live in their bodies. (I'm talking about specifically white cis people here, given that that's all I know; I'd imagine that race and transness colour these experiences in completely different ways. Disability, too; I'll get onto my own experience of that shortly, but it comes in all 32 flavours.)
From birth, little boy babies are encouraged to move more, run about, climb higher. People play more roughly with boys and estimate their strength and resilience more highly. Girls, though, are congratulated on being pretty, and long before puberty and the need to be Hot and the redoubled impact of the male gaze assumed everywhere, they're well aware that looking good is good. Their bodies are ornaments, while boys' are instruments.
To give a ridiculous, but still painful, example: I loved swimming when I was a kid. But then puberty hit, with its attendant body hair and fat in new places, and I was literally too paralysed by my disgust at the thought of myself in a swimming costume to even think about getting in the water again. The fixation on how my body looked made it impossible for me to even find out what it could do.
In the last few years, though, my attention has been brought back with brutal force to my body as an instrument, not an ornament: all the things it can't do make the fact that it doesn't look like some platonic Cosmo-cover ideal kind of irrelevant. Which makes swimming - one of the things it can do, and can do pretty well - a joy to be savoured. When I exercise these days, I'm not thinking about how I look, and I'm not thinking about how I will look; I'm not calculating how many calories this length will burn, or how much walking up these stairs will tone my quads. I'm enjoying the pure physical sensation of capability. Of the body working as an efficient machine, taking fuel in, using fuel to move, and taking pleasure in muscles contracting and stretching and working.
I still like looking pretty, I still wear fabulous outfits and wax my legs and occasionally even stretch to lipstick, but my body, with all its aches and pains and minor ailments and major fatigue is always demanding attention, asserting its physicality, in a way that can't be ignored (I no longer remember what it's like to live without back pain, say) that how it works is the primary mode in which I experience my body these days: how it looks has gradually become secondary. Which is sad in some ways: I'd love to be able to wear heels again, but I know that one extra twinge of pain is likely to tip me over the edge from 'exhausted but coping' to 'word-slurring eyelid-drooping wreck'. But it makes the moments of joy in the body's capabilities all the sweeter. Who cares what I look like? My thigh muscles just took me all the way to the third floor, and it was awesome.