well, to me it means that I am always thinking of my topic of interest, trying to constantly see it with new eyes. It means I'll be thinking about stuff and go "I should write a paper about that". It means writing scholarly articles in your spare time because it's fun. It means being an unabashed, overenthusiastic nerd about your subject.
Of course, all of those things can and should exist outside of an academic setting, but it's a lot easier for me to do those things inside of an academic setting, at a university.