Stupid Me

Sometimes, there isn't any reason for you to feel sad, and yet, you feel sad.
Over-sensitive.
Over-thinking.
Over-negative, in all sense.
Yep, I'm a negative thinker.
Whatever goes the wrong way or didn't go the way it suppose to,
I'll be over-thinking about it.
And yes,
it happened to me, right here, right now, once again.
Stupid brain.
Stupid heart.
It seems like I just couldn't change this f-king attitude.
Stupid me. 
Maybe its true that if you fake a smile and pretend that you'll be happy, and you will be.

P.S.: I'm okay. 

Can someone tell me how to dump away this over-thinking part of me?