So your emotional state really has a lot to do with what you're thinking about and what you're paying attention to. Adaptation seems to be, to a substantial extent, a process of reallocating your attention. Many years ago, we did a study in which we asked people if they would be happier if they lived in California. Most people think they would be, and that's because the climate is better in California. And people in California think they're happier than people who live in other places. But when you actually measure it, you don't find it. Non-Californians are just as happy as Californians. In fact, when you live in a place, you don't think about its climate very much. You don't think about any of its characteristics very much. You just go through your day.
The interesting thing is that this reflects, precisely, a method I've used in the past to get out of depressions, simply to concentrate on something else, put my attention on something other than what was making me depressed. How cool.