Sadness is self-inflicted. You need not to bother too much about every crappy occurrences around you. But then again, you tend to get yourself involved. Happiness is self-induced just the same. As they say, it's just a matter of perspective.
So while you still have the chance to shape your day's mood, choose: would you rather be sad or happy?
Life is good. Life is bad. It's just us who decides.