Grey's Anatomy, Season 6

Meredith:
[voiceover] It's a common belief that positive thinking leads to a happier, healthier life. As children, we're told to smile, and be cheerful, and put on a happy face. As adults, we're told to look on the bright side, to make lemonade, and see glasses as half full. Sometimes reality can get in the way of our ability to act the happy part though. Your health can fail, boyfriends can cheat, friends can disappoint. It's in these moments, when you just want to get real, drop the act, and be your true scared unhappy self.