As an INFJ, I am a wide range of emotions. When I'm on top a mountain, looking out across the landscape, I am quite elated... as I am when I have the attention of someone I want it from. On the other hand, I can become far too worried when contact with said person is limited... and certainly I have had my 'god, I hate civilization' moments where my truest desires is to wander off into the woods and disappear. That, however, might lead to a mountaintop moment, which could be very nice indeed.
Overall, I'd say these things average out... I've never been seriously depressed for more than a couple hours at a time and then only very rarely... but I also haven't really had long stretches of happiness either. It's more neutral with the occasional blip in either direction.