It's not the easiest thing in the world. Writing. Creative explosions may be few and far between. Patience to sort and sift through the brilliant and benign does not always coincide with these creative explosions either.
So what to do when you have a great idea, but you can't muster the follow through?
Write anyway. Writing is art. Writing is habit. The delicacy lies in the ability to stay with it. If you truly want to create a story with depth and theme, a story that touches hearts and makes people think, you must force your habit. You must sit daily and put words to paper (or screen). Then you take that art, that patience, and you sift through and sort out the brilliant from the benign.
It's not the easiest thing in the world, but writing can be a joyous pursuit. You must stick with it.