Happiness is a choice.No matter what people say, happiness is a choice. It's always a choice. I don't mean that you won't feel sad when bad things happen to you, but it's up to you whether to keep grieving about your sadness or to get over it and start living happily. There are many people who always seem sad; they talk like their life is a disaster and keep wallowing in their self pity. It seems like, these people like being sad. The first step towards being happy is to make a choice, " yes, I want to be happy". When you make this choice, you will automatically start seeing good things around you. If you make an effort, mind can be trained to always stay happy.
If you feel sad very often without any reason, then get out of that hole of sadness, created by yourself and make this choice to be happy no matter what the circumstances are. Believe me, happiness is a choice.