Katniss Everdeen: [to her baby] Did you have a nightmare? I have nightmares, too. 
Someday I'll explain it to you, why they came, why they won't ever go away, but I'll tell you how I survive it. I make a list in my head... of all the good things I've seen someone do. 
Every little thing I can remember. It's like a game. I do it over and over. 
Gets a little tedious after all these years, but... there are much worse games to play.

From the movie The Hunger Games: Mockingjay - Part 2