We all have heard this word. It's just a word for someone who has never felt it. But the one who had ever felt it knows how it feels. It's like dark room in which you're screaming for help but no one is listening you. It's that never ending fight that you're fighting with your inner self. You want help but you know that if you'll ask from someone they'll laugh at you or say that you're overreacting.
You want to feel happy from inside but you can't. You loose all the hope from your life. It's like you're smiling in front of everyone pretending like your life is so perfect but from inside your crying and want to say someone that please save me. These words may sound funny to someone who never felt this way. But this is the true feeling that a person feels daily when he's depressed.
At last I want to say nobody chooses unhappiness. Everyone wants to stay happy but the circumstances makes that person so unhappy that slowly he goes into that deep hole which is too dark that he want to escape from it but he can't.