People assume that a person who acts happy must feel happy, but although it's in the very nature of happiness to seem effortless and spontaneous, it often takes great skill. The belief that unhappiness is selfless and happiness is selfish is misguided. It's more selfless to act happy. It takes energy, generosity, and discipline to be unfailingly lighthearted, yet everyone takes the happy person for granted. No one is careful of [their] feelings or tries to keep [their] spirits high. [He/She] seems self-sufficient; [he/she] becomes a cushion for others. And because happiness seems unforced, that person usually gets no credit.
The Happiness Project by Gretchin Rubin