I used to have a standing desk at my last company in the Czech Republic, but as soon as I moved to Japan, I had to suffer through three years of teeny tiny desks with barely enough space to put my legs under, paired with minuscule space on the desk itself, barely enough to fit a laptop and a small external display. Until recently, I have been living in apartments of such size that would not allow me to set up a standing desk (or any sort of office desk for that matter) either, but finally, since last month’s moving to a new house, I could go back to a quite comfortable setup, as shown below 
Just like many commenters above me, I definitely can’t stand all day long, but I try to dedicate at least one hour a day to work while standing. In fact, let me start my daily hour just now!
(I really wanted to get a white display to match the keyboard, and to eventually replace the mouse with a white one as well, but don’t even get me started on the availability of reasonable ultra-wide displays in this crazy country. Samsung, for example, is completely dead in this country due to the idiotic stunt their marketing department tried a couple of years ago, and other foreign brands are no longer available here, for whatever reason.)