When a songwriter at Jack Hardy’s weekly songwriters group would explain what he or she was about to sing, Jack Hardy would say, “Shut up and sing the song.” Abrupt, and to some, rude, but a valid procedural point for a workshop, even more notable in its good advice to the writer.
Let the work speak for itself. If something is important enough, yet is not on the page, or in the lyrics, put it in there. Rework or revise it later if you need to, if what you mean is not conveyed through your magic lattice of words, sounds, syllables.
I’ve stolen Jack’s line when approaching fiction workshops: it applies. I feel very rude ever telling someone to “shut up,” and usually preface it with context. As an imperative to action, “Shut up and sing the song” is simple and worth doing. (I’m talking to myself, too. For years, I whined about how I wanted to write and yet was not doing it.) Shut up about what you want to do, wish you could do, mean to do, intend to do.
Shut up and sing the song.
Rebecca Kuder 
Twenty years ago I took a writing class with the objective of helping teachers of writing become better writers. Teachers, in general, are such perfectionists. No surprise then that we were reluctant to read our writings. Even less surprising was each reading was introduced with an apology; “this really isn’t very good, but…” We only loosened up after adopting the mantra:”Just read the crap.” I still have the t-shirt and have often repeated the advice . Yes, it sounds a little crude, yet if said with the right smile is cheerfully effective. So…. really like “shut up and sing the song,” a nice variation on the theme.
Allan, that’s a great phrase, or mantra. And writers who are honest know that we have to make up something (=the crap) before we can make something good. I can’t recall if it was Anne Lamott or Natalie Goldberg (or someone else) who said it’s necessary to be willing and able to write the sh*tty first draft. Crucial! And you had tee-shirts. That’s wonderful!