Well, my realization was when I was:

1. Going to raids even when I had other things I NEEDED to do, and even when I didn't WANT to go, because my guild needed me.

2. Not playing any other games because I felt like if I wasn't progressing my character then I was doing something wrong.

WoW is a game that once you start playing it, you can't just play for 15 minutes and stop. Just about anything you do takes a good long while. I like being able to play games these days whenever I want, regardless of how much time I have. If I've got 15 minutes to do whatever I want, I'll play some D2 or whatever, and I can just stop whenever I want.