I’m at a mall in Rockville, Md., but instead of enjoying the comfort and convenience of a one-stop shopping experience, I go to a place called Capital Cryo, looking to get some voluntary pain. Soon, the tall cryotherapy tank is filling with a cloud of super-chilled gas: evaporated liquid nitrogen, one of the coldest substances on Earth. [time-brightcove not-tgx=”true”] “Okay,” the technician says.