1. Write anyway. Who cares if it's not great? The depression from not writing at all is far worse than any depression resulting from writing only a sentence or two and terrible ones at that. Just keep writing one word after another. Even if it all gets thrown away later, at least it's something. 2. Read. Read outside your genre. I normally read within the genres I write in -- it's important to keep up with what's going on out there -- but when I get blocked, I find the greatest inspiration often comes from having read a really great book outside my genre. It can be intimidating to read something great that's in my genre, in fact it can be down right overwhelming, so I vary my reading, and my writing is better for it.
3. Eliminate stress. Stress plugs creative energy like hair clogs a drain. I often have to take several days to catch up on the housework because the clutter is sucking away my energy. I also have to make sure I keep my day job current. If the work piles up, I get stressed out -- from grouchy to waking up in the middle of night with panic attacks. And all the while I can't write a single word. Other ways to eliminate stress: exercise, eat right, take a long bath, drink plenty of water.