That Cliche Awkward Crush

I'm currently experiencing one of life's greatest pains. Having a crush on someone way out of your league.
I don't even know how the crush started. Okay, I know exactly how it started. With him walking in the room while I was staring at the door. Then couldn't seem to take my eyes off him. I wonder if I'm being obvious. When he looks up, I look down. When he's talking to me (which has only happened like, once) I hide my inner excitement. By the way, my outside appearance could be compared to that of a zombie.

I'm an emotionless tired girl on the outside.

I'm a hyper active crazy girl on the inside.

 

But even despite the fact that I know what I need to do, and what I'm doing wrong, I can't even bring myself to utter a simple "Hey." in the hallways to this guy.
Why am I so intimidated by him? Guys have always been dopey, and easy to deal with. I've never gotten so worked up over someone.
As cliche as this is, I'm in way over my head.