Funny story: My church organist calls me on a Monday, and asks me to sing at the 8:00 service the following Sunday. This is good. She needs a song choice super fast for the bulletin. I'm at school, and have no access to the Hymnals at my home. This is not good. I do a little digging on the Scriptures planned for that week, and select a quasi-generic song, knowing I could tweak the verses later.
Saturday rolls around, and well, now I had better get tweaking. Turns out the tune I had been humming in my head (O Jesus I have Promised) all week was NOT the tune in the ELW. Ah, the fun begins. Hunted on the internet and eventually found the tune - in a key only a badly-injured tenor could manage, so I transpose it into a key that won't leave people in a paralyzed state upon hearing it.
After that, I start re-writing the verses to really fit the lesson and gospel of the day. I had looked up the bulletin on the Bethany website, and went with the Joshua and Ephesians passages that were listed. Yeah....that was all well and good...UNTIL that Sunday, when Pastor Ron announces DURING THE SERMON that there was an error in the bulletin, and that the Gospel for the day is actually from John! HA!
The verse I had written referencing Joshua was a keeper, but I spent the sermon quickly (and hopefully, not TOO obviously) re-writing something to sing that wouldn't involve all the references to Spiritual Warfare, as found in Ephesians! Took most of the text from the original hymn and made it work. At least I'm ready the next time someone needs a song about armor, battle, and helmets of salvation! :o)