I used to wait for lightning to strike. And when I did find inspiration, I was afraid to change anything about the original way I would write a lyric or melody. I thought, "Who am I to mess with something that's been inspired?!"
As a result, I spent far more time creating than editing. I could just wait until an idea slapped me across the face and then go sit at the piano. The result was a lot of OK songs.
However, I’ve learned that it’s more important and beneficial to be willing to throw out my favorite line than to make the rest of the song suffer. In songwriting, everything is expendable. If a line doesn't support the song as a whole, there is a better way to say it.
With more experience comes the ability to edit on the fly. I've even stopped halfway through vocalizing a line because I realized it wasn't the right direction for the song. Even our initial instincts, when it comes to how a line should be written, are sharpened with practice. The stronger the editing muscle, the more effortless the creative process can become.
Keep writing (and editing),