Well, like I'd said earlier, there were several factors involved, from burnout to chronic pain. I used to be a lot more on the ball than I am now, and even the obvious sometimes escapes me. I've been working on something really big for my campaign lately and I really hope to be more on target than I have in a long time.
As someone who has also been a gamer/GM dealing with chronic pain, personally I would suggest taking it slow for a while and focusing on finding ways to eliminate the pain. I don't know what you're dealing with, but if you can get things under control I bet you'll be able to focus on the game more and find things more enjoyable.
Just make sure that you have the right doctors! I suffered for a long time because the first ones that I went to gave me a completely wrong diagnosis.