I once snatched up a book in the local library that was all about writer's block, and its insights have helped me to bulldoze my way through those walls, yelling in victory.
This book referred to the muse, the element in writers that gets them passionate about their work, as the inner child. Considering that I have been writing creatively in one form or another since I was 12, my muse is roughly 10 years old. I think she will continue to be 10 years old even when she's 57 and we both have trouble seeing the computer screen.
What? Shouldn't every 69 year old play with her imaginary friends?
In addition to calling the muse the inner child, the book advised to treat the muse sort of like a child, writing what and when the muse wants to write instead of trying to force the issue. (I kinda doubt this would work for someone with a deadline, but I currently don't have to worry about that, so I'm just going with the flow.) It helps that I have two series actively moving along to which I can turn. Generally, if the muse doesn't want to play with one group of imaginary friends, she wants to go visit the other set.
Also, I've come to discover that my writing will fizzle to a crawl if the muse feels like this scene isn't going in the particular direction that she wants. When every word becomes a struggle to get onto paper, I realize it's time to take a look back at the chapter I just wrote and decide if this is really how things should be progressing. If not...DELETE. I can always start again, but trying to push a brick wall down just isn't going to happen.
For example, just last night I was transferring all my notes for the Blood Demon Chronicles into one binder and I came across the Vague Outline for Rebirth Alone, I put the outline on a brand new sheet of paper, all nice and shiny...only to discover that I hated it. I'm now 12 chapters into a new outline for this book and liking it a whole lot better.
I've read several posts on the internet that claims Writer's Block is just an excuse not to put words to paper, but I want to add my own caveat to that. Writer's block is an excuse only if you don't struggle against it until the clog is fixed. I imagine everyone has days when they have so much trouble getting words to flow that giving up seems like the only way to save themselves from an burst blood vessel, but pushing through that feeling is what makes a successful writer.