Nervous?

Today I will meet the mass choir for the first time as a director. I will teach my song "We pray". On monday and tuesday it seemed like the singers were tired off and on. I don't know if it was because of the heat, or because they did not like the songs. So I wonder if I will make them fall asleep with my song, or if I hit the nerve that makes them tick. Either way I am going to do my best, and have fun with it!