Well, I suppose I do know why any two Cs played together sound rather boring. And I know why a C and a Csharp played together sound wincier.* But why a tune can lift the spirits, or induce a deep healing calm, I've no idea.
But it can.
I reckon it's worth trying, don't you?
Thing To Do Today: be musical. If you can't play a conventional instrument then you can sing, and if people say you can't sing then I'd suggest assembling some non-sentient objects of various shapes and sizes and hitting them, though probably not hard enough to break them.
Or you could always play a carrot:
The word music comes from mousikē, belonging to the Muses.
*Basically, if you pluck a tight string it will vibrate all the way along its length and a note will sound. If you push the string against something hard at a point exactly half way along its length and pluck it again, the string will now only vibrate along the half of the string you've plucked. This will make the vibrations half the length, too, and the note much higher.
As it happens, if the first note was a low C, say, the second will be a C, too, though a higher one. Now, because the vibrations of the second note are exactly half the length of the first note this means that the two sets of vibrations fit together really nicely, thank you, and this makes the two Cs played at the same time sound calm and sweet and inevitable and even a bit dull.
The more complicated the relationship between the length of the string needed to make a note and the other notes that are playing at the same time, the stranger the noise will be.
Fifteen C vibrations go into sixteen C sharp vibrations. This is about as strange as it gets in Western music.