But in the last few years, research has begun to point to a different set of biochemicals as the cause of runner’s high. Endocannabinoids are like the body’s version of THC, the chemical in marijuana that makes you feel, well, high. So is runner’s high an actual high? Feeling calm and confident during such an arduous pursuit was no doubt an evolutionary advantage of the runner’s high. For example, past studies have found that as many as a quarter of endurance runners have reported never experiencing a runner’s high.