Is it true

I've found that if I'm not happy, and I smile, I become happier. I feel it. If I'm grumbly and I catch myself, I will force a smile that will settle into a genuine one. Of course, experiments on onesself, and on one's moods, are sketchy, but I suspect its true that:
1: You can control your mood and, by extension.
2: You can choose to always be happy (try to convince me that that is a bad thing).

So; turn away from the internet for just a second. Concentrate and determine your current mood. Then smile and see if you feel any difference. Try forcing it, even for a few minutes. If you stifle a giggle at any point, even if that giggle is "Man, I must look ridiculous", than I submit that it worked.

So why not?