Since the 1980’s runner’s high was always thought to be caused by chemicals called endorphins. New studies now suggest that endocannabinoids are responsible. Endocannabinoids are a group of chemicals in the body that interact with the same systems in the brain that THC in cannabis does but your body naturally makes them. They are involved in soothing anxiety and reducing pain sensitivity. Although achieving the feeling on long runs can put your mind and body through some intense suffering.