as for me, it depends on the songs. I also sing some words.
It sometimes gives me some kind of motivation.
But in our class, we have like a chorus in the front line
They are funny to hear...
Another BP, BA, BC, BJ and RPM freak Fitness Show in Paris : 09/19-20/2009
http://animoto.com/play/0lmvNUk7jNu5XyBwnOiAIA
http://www.youtube.com/watch?v=cgv4bVJheBE