Roughly translated: your back will hurt.
Now, I know this is mostly my fault. I came to a country with the average height of males at 5'5" (165 cm), and the average height of females at 5'0" (153 cm). Whereas in the USA we stand at 5'9" and 5'4". I knew this full well before coming. And for the most part, it really doesn't affect your experience too much outside of the home - department stores, grocery stores, banks, especially train stations were built with more than enough buffer zones in ceilings and doors. What I notice most, however, is counter height. Try washing your hands, cooking dinner at home, bending over to look at the menu next to a register. Where you might have only slightly inclined your head and upper back in the USA, here you will go full-throttle, completely bent over.
It takes its toll. Couple that with a few archways at some stores (definitely had to come up since I'm almost 6'1"), the abundance of hard matresses for "western-style" beds, and the thin padding on house slippers, and I'm not at all surprised that I see people over 70 completely hunched over 100% of the time. I'm not joking about that - at first, I thought it could have just been their previous business practice, with lots of bowing, but take into account these small things and you too will be shaped like an upside-down "L" if you stay here long enough.
I should point out, however, that this is merely a side note. Not even a complaint, just more of an observation. The experience of living abroad and in a country as rich in culture as Japan is more than enough to overcome these slight inconveniences. However, if I get the chance, I'll try to catch a picture of some of those older people I mentioned. It's a little daunting.