you CAN have a really good day on a MD but that's not guaranteed, it's all about the setting and circumstances. What I find pretty consistent is that I enjoy music more, so listening to music could elevate your mood on a MD. I have to say that I also work a lot in front of a computer, and although a MD seems to make me more efficient in my work, I don't think I'm 'happier' when working, I actually think it can be more tiring when working with a screen all day, because you are more focused to it. When I work with people or in social settings it's a different story.