I can chime in with the "music" folks. It's amazing much of an effect background noise can have: I was working one day in a coffee shop, and plodding along nicely with your standard coffee-shop alt-rock playing in the background.
Then, at some point the music switched to bebop--really fast jazz. I had been sufficiently focused on my work that I didn't notice the switch, but I did notice that I was typing about 50% faster! It didn't cheer me up, exactly (I didn't need cheering up, fortunately), but it did something!
In more general terms, I strongly believe that much of what we enjoy in music are the associations we have with other things...there are plenty of pieces that make me feel better, not necessarily because of the tempo or anything, but because they remind me of another time I was very happy.
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