This is amazing. If I understand it correctly, the study found that what you think about when your mind wanders affects your mood (seems obvious), but the content doesn't directly correlate to the change. In other words, certain negative thoughts can make you happier, and positive thoughts can make you less happy. Generally, thinking about the future and yourself leads to an increase in mood (happier) even if the thoughts themselves are negative.<p>One of my side projects is an application to track whether or not people are feeling positive or negative correlated to external events* (news, weather, location, situation, etc). Users (all 2 of them!) record how they feel by entering a short description of their mood. Recording correlation of internal thoughts is on the roadmap. This sort of research is hugely interesting, and potentially very useful for improving mental health.<p>* If you have 30 seconds to spare you can help make it better - pop over here <a href="http://usrlab.com/mood" rel="nofollow">http://usrlab.com/mood</a> and rank a few words by clicking on the most relevant smiley face. :)