A poem of mine has a line in it that begins, “What I really need to save are breaths” I just spent many insomniac minutes trying to convince myself anew that it shouldn’t be, “What I really need to save is …” even though breaths is plural. It just looked so wrong. After consulting several grammar sites, I mostly had to concede — but I was still trying to fabricate exceptions. Somehow, it seemed different because the sentence began with “what.”
Then I tried a trick I taught a GED student I tutored years ago: Flip it around. Would you say, “Breaths is what I really need to save”? Well, no. But now, as I type this, it looks wrong all over again. Perhaps I should go back to bed. What I really need is/am/are sleep.