Many have mentioned gray, cold, wet weather-- well I live in Florida and it's the same here. I believe these feelings, inertia we experience is in part from running on adrenalin for extended periods. Also realizing how quickly the year has past and those pesky regrets. I try to mentally list the blessings when these feelings surface. Some will say "well that's age talking" (I'm 58), but my 13-18 year old students talk about the same feelings! I stroke and sort my fabric, look at my magazines and books with an eye to something new- a project, technique or skill I've avoided because I didn't have the time to focus on it before. Seems to help me.