How does one stay happy? As Anne Frank says in her diary, there are two ways you can go about it. One is to count your blessings, think of all the nice things that have happened to you, and feel good about it. The second is to look at all the misery in the world, especially at the people who are in worse conditions than you are, and, feel thankful that you are better than most. Anne says that while her mother always adopts the second method, she prefers the first, 'cause, when you take the latter path, you are continually reminded of all the misery in the world.
I agree with Anne. Though most of us generally go about in the second manner, it ensures that your happiness is dependent on the continual misery - greater misery - of others. It is only when you are convinced that there are people who are suffering more than you are, that you start feeling a growing sense of sadistic pleasure. But, if you go by Anne's choice, you see that your happiness is independent of other factors. You rejoice in the person that you are, in all the nice things that have happened so far to you, in all the joy you see around you - and, this means that you can always be happy, no matter what, for you are the person that you are, and no one can erase that.