Being depressed is like being trapped in a small closet that smells bad and is dark and musty.
I have no idea what you're going through, but trust me, depression never leads to good things.
As I've said before, being positive is not something you can achieve all the time because things such as failure, disappointment, and heart break still exist... BUT.
Everything will always be okay in the end.
And if everything is NOT okay, then it's not the end!
So don't worry, and keep your head up because your journey still isn't over. You have a long life ahead of you, and even more so with dreams and hope. Don't let your bad circumstances shape your future, or yourself. Instead, let it make you stronger!
There will always be someone who wants you to fail so disappoint them ;)