And that's all well and good, but don't forget reading. If you're stuck in some writing project--or even if you aren't--reading can be so good for you. For one thing, it's FUN. Different places, interesting characters, magic, adventure, extraordinary events... it's all there for the taking.
But I'm not just talking about reading good stuff. All sorts of reading can be fruitful, even if it doesn't have the FUN payoff. For instance, if you read a book that ends up being dreck, try figuring out what you hated about it. Maybe it was one glaring problem, or maybe it was a whole laundry list of ghastly awful errors. Even if it was terrible, it can offer you insight about what to look for in your own writing. Who knows? You might actually be committing some of the same faux pas yourself.
I also find it fruitful to read other writers' rough stuff. Perhaps they venture into a genre I haven't tried, or do something magnificent with a scene. Maybe their insight helps me figure out a problem in my own writing project. Even if their stuff isn't good at all, helping them by offering feedback and marking errors not only helps them, but also helps me edit my own writing more effectively. Since the stuff is rough, and feel more able to note what scenes falter, to see where the momentum shifts or drops out completely, where characters disappear for too long, or where scenes aren't descriptive enough (at least for me).
Reading work in-process helps me see how to affect my own process more, how to make my work better once I return to it. As an added bonus, it means other writers owe me, that I'll have faithful, honest readers to offer me feedback when I need it. That is probably the best result.
I finished my play this morning (hurray!), so now I'm off to read a long list of other writers' drafts. And I'm looking forward to it. I should learn a great deal from the experience.
How long has it been since you've helped out a fellow writer?