Relating specifically to the sensation of boredom, and not to the larger issue of writer's block, I've noticed some trends over the past 18 months.
When I have become bored, it's because I was forcing the narrative to stay in its channels, headed toward where I wanted to go. For example, I was afraid remaining in one setting for a long time would be dull, so I threw my characters on the road - classic quest, right? I hit a wall after a while, listless, no spark. @Not Lu
gave some sage advice phrasing the issue this way "Do I want to write a quest story? (I never did) or do I want to write about how a character tried to make things better, but destroyed the world?"
I won't bore you with my other examples, but the point is made. For me, getting off track toward what things are supposed to be, toward what I logically think they should be, bores the hell out of me and makes my writing just as dull as one would suppose. Forcing my face into the cold water of pure inspiration, discomforting as it can be, wakes me up and makes the ideas better - which is exciting and aggravating (see my writer's complaint post
) but not at all dull.