I was talking with a friend a couple months ago about how we were told we could achieve anything in life and what a lie that turned out to be. I find running to be a good antithesis to that. It's about being the best the individual can be and finding little value in comparing against others.
It probably applies to lots of things. Running is easy to measure, but I think it could apply to anything where someone values their own ability, even if that ability provides nothing to the subject. Maybe especially if it provides nothing. Growing a topic invites scrutiny which invites self doubt.
Basically I think everyone needs a hobby, something where they're doing something. It doesn't need to be active, but it should be something where they're bettering themselves.
I feel happier since I started running, but I don't think it's running itself, I think it's from having a hobby where I can feel myself being more capable.