Another favourite from TFIOS:
Much of my life has been devoted to trying not to cry in front of people who loved me, so I knew what Augustus was doing. You clench your teeth. You look up. You tell yourself that if they see you cry, it will hurt them, and you will be nothing but a sadness in their lives, and you must not become a mere sadness, so you will not cry, and you say all of this to yourself while looking up at the ceiling, and then you swallow even though your throat does not want to close and you look at the person who loves you and smile.
-Hazel Grace Lancaster