The great thing about dealing with a potential burnout is knowing that the malaise will eventually subside and you'll feel all rejuvenated and hyper like an Asian Giant Hornet on speed. Ironically, I think a helpful way of doing it is to look at your work.
Because I'm so job-hungry, I updated my curriculum vitae today (I have five). I saw on my writing CV that I had six credits, most of them from within the last couple of years. The weird thing was that feeling of it dawning on me that, yes, I have been writing. It doesn't seem that way when you're editing at 11 PM or clawing your way towards your laptop at 6 AM when the sun's just coming out.
Then I looked at my binders of writing and saw that I had quite a bit stored up just from the last few months. Short stories. Articles. Novel work. Notes for upcoming projects. A lot of it's still raw, but some are nearly ready for submission.
My point is that rather than feeling overwhelmed, I was pleasantly surprised to see evidence of hours, days, and weeks at the keyboard. Unfinished? Yes. But a vague fog? Hardly.
This doesn't sound like something I'd normally say, but if you're feeling like the work is getting to you, turn into a "glass is half-full" kind of person and take stock not of what lies ahead, but rather how much you've got behind you. Many times, you'll see that the end of a project is closer than you think, and that'll get you charged for pushing the rest of the way.