Grey's Anatomy, Season 4

Meredith:
[voiceover] In the hospital, we see addiction every day. It's shocking how many kinds of addiction exist. It would be too easy if it were just drugs and booze and cigarettes. I think the hardest part of kicking a habit is wanting to kick it. I mean, we get addicted for a reason, right? Often, too often, things that start out as just a normal part of your life at some point cross the line to obsessive, compulsive, out of control. It's the high we're chasing, the high that makes everything else fade away.