Perseverance

Do you ever feel like you can't get on the right track with a song?  I wrote several lines for "Overflow" which I  can't decide whether to make the verse or the chorus.  I also am having trouble finding the right chords for the melody.  I can hear what I want in my head, but when I get my guitar out and play, the melody changes.  I'll keep working on it.  I really like what I have right now even though it seems to be a hard process.  Some songs seem to write themselves in a course of 5 minutes, others seems to take 5 weeks.  Perseverance!