I think I did that with 2OO3AB one day, and I really felt the emotion involved, but mostly I try to concentrate on singing in the right key and at the right notes

I surprised myself today by doing it with AFL, but then I think it was easier than I thought because I've got the sheet music for Bat 2 and it was quite easy to find the notes vocally once I knew where they were on the piano and after each other :)
On a completely different topic, I've just seen the man (doctor, obviously) who saved my life when I was a baby on the local news for the first time