Mind.

You can't always feel good about your life or even yourself, no one human could do such a thing.
A mind is a very powerful thing. It can make you think things that send you into a downward spiral, things that may not even be true, your mind evaluates situations that you are in, giving you the directions to what's right and what what's wrong. Sometimes it sends you in the wrong direction, and you begin to over think everything which is never a good thing Believe me!
Your mind then never rests, it keeps you up all night weighing up all the different things that could be happening. But sometimes on the other hand, your mind can be a wonderful thing allowing you to enter a place that is entirely your own. Some say that this is called your imagination. I don't think it is. Without a mind there is no such thing as an imagination you still have to think about things when you are imagining and that is what a mind is for.
So here's a word of advice from myself to you; don't always believe what your mind tells you, sometimes it becomes distorted and sends you in the wrong direction.