Being a type 2 diabetic I'm not sure if this particular writing related 'ailment' is physical or mental, but I'm looking at ways to banish my sudden sags of enthusiasm that hit me like a freight train after about three hours of writing. Admittedly it could be one of the downsides to polishing as you go, which is a habit I can't get out of of. I've accepted this means my daily word count will be low, and I'm fine with that, but I wonder if has anything to do with the sags. They hit me around the three-hour mark and can strike in the middle of a sentence, let alone a scene. When they do hit I get an urge to stop writing which is impossible to fight through. My body slumps, I feel completely fatigued and tired (as though I could curl up and sleep right there and then) and all my desire and enthusiasm seeps away. I save and shut down the document and feel a great release in doing so. I pick up a few hours later, but by then can't motivate myself to get back behind the keyboard.
Sounds like me after five minutes of actually let's not go there I think you were right to stick bunny-ears on ailment. It's pretty natural for humans to want a change of pace after a shorter time than you're talking about, so this might be your brain telling you how to keep itself healthy. Possibly you'd have more overall success if you made a habit of taking breaks/changing activities more frequently (e.g. ten minutes every hour) - you might get stuck back into it sooner, for more overall writing. Despite that, if you wanted to build the discipline anyway, maybe mindfulness practices would help. You teach your conscious brain to kinda compartmentalise all of those negative feelings, mentally observe them, recognise them for what they are - electrical impulses inside your skull that don't mean anything in and of themselves - and move on. Or something. I'm no expert, a bit sceptical and haven't had much luck with it myself, but I've seen people who can put up with pretty painful things by thinking in that way... I suppose blood-sugar issues are possible (do you have a glucometer you could test yourself with or anything?), but I suspect it's more psychological. Sounds like you're sticking to your writing a lot better than a certain non-diabetic I'm intimately familiar with, so...
Ooh, I take breaks. I'm World Champion Procrastinator and pull myself away from my writing with any excuse I can come up with. I'm certainly not sat typing away at my novel for three hours. I dunno, maybe it's just as simple as my brain telling me I've spent enough time in my novel's world for the day. And I'm sure it's partially blood-sugar related. I have the kit for testing my levels, but rarely use it as I know what it will say depending on how I feel. It will be high if I'm active and alert and low if I'm in a slump. My body is a bit like one of those years old batteries that won't hold its charge any more.
