It does not necessarily come naturally. When I first got into the game the temptation to keep playing was strong and I'd play half the day away. It became a contention in our marriage with the amount of time I was putting into the game not spending with my family.

I finally came to the conclusion that if I wanted to continue to play I had to limit my game time. It does help that I got my wife into the game, but she doesn't care to play nearly as much as I do.

I guess you have to keep priorities and remind your self of them regularly. Wife & Kids are more important than WoW, but maybe not exercising... oh yes I'm starting to let exercise cut into my wow time but that's another story.