I have been reading Temple Grandin's Animals in Translation and she spends a lot of time talking about emotions, particularly emotions shared by people and animals. She discusses curiosity as an emotion. I had never thought of curiosity as an emotion, but I guess it is, as she describes it: a sense of excitement and anticipation about the things around you.
Which strikes me as the opposite of depression, and part of why going for a walk or drive, or taking a trip, can help a person shake the blues.
Just as I thought: you can run away from your problems.