I'm barely a noob (did run/jog 15 miles once), but I love running and when I reach groove, it's a bit more than groove. I feel a strong uplift. Not a high, but suddenly pain and even effort just vanish from my mind and I just 'fly' contemplating the world. It's a very happy sensation. Unfortunately it's also a zen exercise because it's usually when you become aware that you're 'flying' that you start to drift away from it. Maybe a relation between not running for the sake of it, but running while thinking of something else.