Sometimes we can get stuck when we look at the big picture too much. That's when it's time to break things down into smaller chunks. And even that can be overwhelming at times, when there are so many of those smaller chunks to be doing.
To get unstuck, I think about it just enough to say, "What's the next step?" Once I am able to answer that question, I don't worry about anything else at that moment. I have direction and am able to move forward again, by simply taking that next step. When that step is completed, I repeat for another step.
One step, and then another... and before you know it, you realize you're actually getting somewhere. :)