For me Christmas is special because it isn't 'normal'. It's a couple of weeks of having a tree, decorations, family and friends' visits and lots of food (and drink for those who partake). If that stretched to a month, it would lose its special status, for me, anyway.
I agree that the post-Christmas months can drag more than the run up to the holidays, as there is nothing to look forward to. Christmas does concentrate the mind by giving the winter some focus. After Easter, however, the days get noticeably longer and the weather starts to improve. Then there's a brief summer, and it all starts again
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