When I was an emotional teenage, my mother said to me, "You're wearing your heart on your sleeve. You have to fake it until you make it." I was horrified at that comment! FAKE being a good mood? That was akin to living a lie - something I vowed never to do. If I wanted to be miserable then so be it.
Experience, on the other hand, has proven otherwise. Have you ever been depressed? Sullen? You begin to get comfortable with it, wearing it around you. You actually, in some twisted way prefer it. It's easy. Warm. Life seems to have less complications. Oh, you're not exactly happy - but hey, it's working, so why mess with it, right?
"Fake it until you make it," isn't about pretending to be someone your not any more than getting comfortable in your bad mood/depressive self is your true self actually revealing itself. I've experimented with this over the years, and when I 'wake up on the wrong side of the bed,' have a 'bad hair day,' whatever - and propagate that mood throughout my day, I find that I'm generally grouchy, unpleasant, and irritable. Furthermore, I mutter things like, "Why me?" Or "Figures." And NOTHING EVER TURNS OUT LIKE I WANT IT TO.
But if I force myself to smile and be pleasant (mind you, I'm not in the mood) then not only are all my expectations exceeded, but in a short period of time, I really am in a better mood, no matter what external influences are exerting pressure on me! You see, it's not about wearing a 'happy face' masking what you really feel inside, it's more a technique used to pull yourself out of a slump that (when experienced enough) you know will go absolutely nowhere and plop you smack dab in the middle of misery.
You know that feeling that comes along only every once in a while when you're just in a fantastic mood? Imagine holding on to that for weeks, months, even years. I am a firm believer in - because I experience it every single day - getting whatever you want, whenever you want it, every single day, simply by working hard and fighting daily those forces which try to bring you down.
Of course I could have built this entire philosophy on something my mother said simply to be flippant and dismissive. Who knows!