I am really keen to start writing some lyrics. I have always written instrumentals but I sing (a little) so would like to have some lyrics to put to a song.

This is what I have come up with so far. It's just 4 lines but I feel like it needs another line to finish this "verse" off.

The summer has faded into the fall,
The nights are so long, darkness covers us all.
The cold creeps on in,
Warmth waning within...

I feel like this last line needs to lead into another verse or bridge which will develop the story, but I have absolutely no idea where I'm taking this!

So my question is, how do you stop yourself coming to a stand still like this? Do you have a story or theme in your head to start off and then write the lyrics from that?

Also as a side note, if this was developed, what do you think of the 4 lines written so far?

I think that what you have is good. But on the topic of story and theme, if your looking for story this probably won't start you at least for just this song, this would be more of a song for like a concept album.