I think it's pretty safe to say that it does release endorphins, as that happens rather easily under pleasurable conditions. Feeling all relaxed and with a lower heart rate sounds a bit more pleasurable than how I experience shaving. As it requires my full concentration, both to shave and not to get hurt by my interfering cat, I don't think of all my little insignificant troubles that otherwise keep playing through my mind. It's relaxing for my head