Here's a specific problem -- solve it.
Folks in the members area have been talking about songwriting, which is simply the most challenging part of anything you will do in your music career. So it was neat to stumble on a post about Eno on the Microsoft Sound. By letting go of some bigger songwriting challenges and focusing on a very curious exercise -- composing an under-four-second start sound for Windows -- Brian Eno actually reinvigorated his craft.
If you're feeling stuck, what kinds of simple challenges can you lay out to get your gears moving again?