I've spent years dealing with depression. One of the things I had to figure out was that I was the one driving it. I was causing it to happen to myself. And once I recognized what was happening, I found I could stop it in it's tracks. It took work, but I have improved immensely.
One of the things I learned was that happiness is a choice. Too often we put restrictions on our happiness. "I'll be happy when..." or "If only this would happen, then I would be happy."
I decided to choose to just be happy. Screw what happens to me, or around me. Doesn't matter if the world has problems, or my neighbor does. Doesn't matter of that person cut in front of me. Sure I can still get pissed, but I still maintain my happiness. Because it's a choice. A decision I made for myself.
Although being happy doesn't mean I'm satisfied. I keep that drive to improve myself. To get stronger, healthier, and wealthier. (Personal goals.) Neither am I satisfied with the way the world is. There's a drive to make the world a better place, even if only on a small scale.
Too many people think happiness is the goal. I say it's the journey.