I luckily haven't lived in that sort of climate, but if we get a week of drizzly grey days, or even if I get stuck behind my desk and don't look outside enough it affects my mood.

I think no matter what the weather, it is very important to get outside daily, and see something natural. There have been many studies that showed people in hospital get better much faster if they can see trees and living things from their window.
Perhaps setting up a bird feeder might suit some people? One that you can top up daily at a regular time. If you can't do it where you live, perhaps a handful of seeds set somewhere outside during your work break? A friend does this at breakfast time through winter, and says it really lifts her mood. She feels part of a world beyond the human drudge.