IME, the best cure for winter misery is getting outdoors, which seems paradoxical to them as ain't tried it. I'm a part-time ski instructor, so pretty much every winter weekend is spent outdoors. While it can be harsh in the moment, I've observed that I get many fewer illnesses than my co-workers, who mostly tend to hibernate, and my Gray Cloud of Doom is a lot smaller and more transient. I think the more you can get out there, the more endurable your winter will be.