Stuck in my mind.

There are times when I just sit there, and miss writing but have absolutely nothing to write about. I'm stuck in all the short stories and novels I've started. I sit there at my computer watching that line blink on a white screen, thinking...
My mind wonders to nothing, it draws a blank just a white screen. Sometimes it even wonders off too intense thoughts about life, and space, and how I'm never going to experience space stations, going to space or actually knowing that the theory of aliens is no longer a theory. I start thinking about my life, and become aware that i'm alive right now. Will this be the only time i'll ever be alive? of course it is. I'll never have that feeling of knowing I'm alive, never sense anything again. I'll just be gone. Like being asleep forever with no dreams.
My mind then will usually wander to religion and God, and all the other types of religions, and well you know how intense that can be. Especially if you have absolutely no clue what you actually believe just yet.
My mind wonders and wonders, but never comes up with anything to actually write about. I become paranoid of stealing other peoples ideas, I'll start to think everything I write is crap, like even this here. I'll freak out when I have the perfect topic, but think i'm not smart enough to continue it so I just end it at the topic and then push it aside. I feel like my grammar and spelling and idea making is not enough to make an actual story, or i'll make it extremely crappy. I never know how to end anything properly, and the stuff I've already wrote sounds like shit.
I freak out tooo much!