Play a song you've never heard before

I picked up the guitar, and started singing a song. The song didn't exist. I was actually making it up, but I was kidding myself that the song was already there. All this stuff came out. Some of it I couldn't remember, so I mumbled those bits. Then I went into other bits which seemed to have something like words, or bits of words. I kept going and didn't stop, even if I was really unsure about the song or where it went next.

As soon as my brain took over and stopped my auto-pilot, the song became useless and formulaic.

So I went back and tried to remember the good bits.

I have used this kind of 'surprise yourself' technique with great success. I almost have to catch myself 'off guard' to do it, and I need to have had a few hours break from songwriting that day for it to work, or I fall back into what I was working on previously.

Like I said, as soon as you start thinking - it's all over. However, the more you practice this, the better you get at it. It becomes about sounds and shapes instead of words, and the panic of trying to keep going and do the next bit even though it doesn't exist can stop you thinking too much about it. As soon as you think to much you'll probably fall into an old chord sequence or sing an old melody.

Every now and then, just pick up an instrument and see if a song is there. Sometimes it is.