When you stay "locked in" long enough that the pain flips into pleasure, your body is making its own version of weed. Same chemical family as the THC in marijuana. Researchers nicknamed it the "bliss molecule."People used to credit endorphins for runner's high. Endorphins can't even get into your brain. They're stuck in your bloodstream, too big to cross from your blood into your brain tissue. In 2015, German researchers found what was actually doing the work: your body's homemade weed chemicals