I don't really believe in writer's block. I agree with the acquaintance who says it's an indulgence of amateurs--when you've got a contract with a deadline and you either turn in a manuscript or return your advance (which you've long since spent), you may find writing difficult and your results unsatisfying, but you do it anyway, because that’s what professional writers do: write.
However, I do believe in the realization that your current work is of such poor quality that you should abandon it. (Don’t delete it--the idea may be worthwhile even if the execution isn’t.)
I believe in inadequate preparation.
I believe in inadequate organization, too.
I believe in writing yourself into a corner so tight that you either need to start over or abandon it. (“Damn, this only works if it was all a dream!”)
I believe in lost enthusiasm for a particular work.
I believe in lack of focus, in not knowing what your story’s really about and why these characters should tell it.
I believe in increasing boredom with an entire genre that’s become too familiar.
I believe in well-crafted characters you don’t want to spend time with. (Nobody else will, either.)
I believe in stories that require a daunting amount of preliminary research before you can write. (“Sure, that’s it, a police procedural following a serial killer who’s targeting milliners in 1910 Belgium!”)
I believe in shyness and lack of confidence that makes seeking expert advice or background hideously difficult or impossible.
I believe in not knowing how to start, or where to start, or even if you should start.
I believe in concluding that your whole concept is stupid, immature, derivative, impractical, embarrassing, too personal, legally actionable, or any of a host of other fatal flaws.
I believe in realizing that you're not as good as other people, the ones who ought to know, like teachers and fellow writers, think you are.
I believe in realizing that you're not as good as you think you are--or ought to be.
I believe in that ‘what’s-the-use’ attitude after you learn that your first several stories or novels are probably going to be pretty bad.
I believe in the inability of the writer to bring to life characters well beyond their experiences (regardless of research)--and I believe in the incredible frustration of being young and bursting with ideas that you shouldn’t tackle yet.
Now, any of those can stop you dead in your tracks and keep you stopped. The question then becomes, how can you get started again?
Give yourself permission to write crap. This is huge, letting yourself write something you know isn't good. Write it anyway. Nobody needs to see it. Written things can be revised or rewritten to improve them. The blank pages of the 'blocked' remain blank.
Change your writing environment. Try something radically different. If you write on your computer in a quiet room, try a spiral notebook in a park or coffee house, or ruled paper on your mother’s dining room table. (Not recommended: your blood on walls.)
Perform writing exercises. (Google for thousands of them.)
Move physically. Play a sport, go for a walk or run, swing on a playground, whatever you like, but get your blood pumping. When it's racing through your body, the brain gets plenty of oxygen--and ideas.
Give yourself blocks of unstructured time when you’re not likely to be sleepy. Find a quiet place, think about your current writing project, and let your mind wander. Rein it back to the subject as needed. This can be combined with physical movement--a long walk may be an idea wellspring.
Follow the BIC method and write daily.
Stimulate your mind with new experiences. If you're a movie fan, see a play or watch street performance. Hear live music rather than CDs, or listen to something in a genre you know nothing about. Eavesdrop on or observe people unlike most of the ones you know. People watch (and invent lives for passers-by). Attend a sporting event (any kind, at any level) where you don't know anyone and watch the crowd rather than the players.
On waking, jot down the surrealistic snippets of whatever dreams you remember. They don't mean anything, IMO, but the odds are good that they're packed with drama.
Just do it. You don't want to be a self-indulgent amateur, right?
Maryn, who's given this pep talk before