What was it I was most worried about? It was kind of all of it, the energy a concert requires, both in terms of the crowds and the output from the band. I heard myself say, "I'm too old for this!" which is when I knew I HAD to go. People do these city things all day long, in much bigger cities than Atlanta. If they can, I can too.
It's a good rule of thumb for me, that if it scares me, I have to do it. Irrational fears, not real ones. Like I don't care who says what, I won't bungee jump or jump out of an airplane. I won't walk on burning coals, either. But when it's something anybody can do, and many people do every day, then if it scares me, I'll make myself do it.
Singing on stage was like that. I did it years ago, in a bar, so hopefully I was drinking. But only a few years ago, the man running our local jam session (now closed, alas) saw me singing along with the players on the stage and said, "You're on next."
There were probably about ten or fifteen people in the audience, but it didn't matter. It still freaked me totally out. I did it though, and since it scared me so much, I went back the next week and did it again, and again and again, until now it doesn't bother me at all. Well, hardly at all.