The Beatles were wrong. There IS something you can do that can't be done. Figure out what that is and do it. Because if you don't ... no one will ... and the Universe will eventually end with that thing un-done. Maybe it's a poem, or a painting, or a song, or a theory, or a motion, or a thought, or a view, or a sound, or a way of being. Figure it out ... do it ... no one else can or ever will.