I don't think it's a sign of impending death! Except that we all hurtle towards that end all the time. :)
Partly the weather, partly the time of year. I'm much the same, but have the excuse of having been fairly ill for most of December.
I know a group of writers who meet occasionally and informally, drink a lot of coffee and talk about where we are and - all sorts of things. They suggested that I really needed to type up a novel (60,000 words) I wrote many years ago (no p.c's. around in the early '80s). That was 2 months ago - I started last night!
I'm surprised at how basically good it is, but I can see the language used is old-fashioned, so I'm updating as I go. Then there's the current Homework for another writing group - and the notebook full of ideas.
Hope this is relevant - I have so many things I still want to do and I have realised that I have limited time left in which to achieve them. The size of the tasks I'm setting myself almost frightens me into immobility. I know I'm not alone in this. Good luck! :)