For me it's the physical labor involved in things like getting the tree, setting it up, doing other decorations, getting the Christmas dishes out, wrapping stuff, etc. To me, all the rest of it is very nice, and I enjoy it all. It's just that thing of not always feeling like getting involved with a lot of physical labor but knowing that if I don't do it - that's it. No Christmas atmosphere. I live under some kind of bizarre stress anyway, and then (and I don't want to come across like I'm trying to be a martyr here) I've been getting over a very serious leg injury for quite awhile now. So the physical stuff that one wouldn't even think of until the need for it makes itself known can pretty much make me feel like I'm (forgive the hyperbole and inappropriate reference here) in the Bataan Death March. I can't help it.... Every year since my father died in 1973, all the physical stuff involved with family Christmases has been my department. First, it was the tree for my widowed mother. Later, it was Christmas for my kids (and I really liked doing it at the time, although I didn't prefer the physical stuff on top of everything else there was to do then either). Now, the kids are out of the house, and I'm happy to still make Christmas for the whole family, but I do have to say that I'm not particularly thrilled with the physical stuff involved. (Besides everything else, the fake tree cuts up my hands, and I have to live with that for - like - the rest of the Winter, it seems.) Oh.. Correction: One year a family member put up a real tree, so I only decorated it (but it didn't smell, and we don't like the idea of real trees growing and then being cut down anyway). Another year, one of my sons happened to be here (none of the kids live very close or have a lot of time), and he set up the tree that I'd already dragged up from the basement.
Other than those two exceptions, it's been all the physical stuff and the dragging up, setting up and decorating of the tree for a solid - what - 39 years now. Well, on top of all that, it was Christmas decorations and related stuff that are the reason for the leg injury that's taken just about three years to even get close to back-to-normal; so you can see why a) I need to vent about how little I like all the physical stuff, and b) why I'm kind of sick of that end of Christmas at this point.
Still, when it's done and the day is here, it's mostly worth it (well, except, maybe, for the 3-year leg thing). :/