Runner’s High

A state of euphoria while running, commonly described with feelings such as “pleasantness”, “inner harmony”, “boundless energy,” or even druglike “orgiastic” sensations. See also, and contrast with helper's high. See also zest.

Reference:

Boecker, H., Sprenger, T., Spilker, M. E., Henriksen, G., Koppenhoefer, M., Wagner, K. J., ... & Tolle, T. R. (2008). The runner's high: Opioidergic mechanisms in the human brain. Cerebral Cortex, 18(11), 2523-2531. https://doi.org/10.1093/cercor/bhn013