"You may be disappointed if you fail, but you are doomed if you don't try."

The meaning of the Beverly Sills’ quote to me is to not allow the possibility of failure hinder you from at least trying to accomplish your goal.  If you don’t make an attempt to be successful, there is no possibility of ever reaching your goal.  Not trying is what dooms you.  If you fail, just keep trying until you are successful.  Each failure can be a taken as a learning experience wherein you discover what works and what doesn’t work.  Try accomplishing your goal with the knowledge you learned from the failure to become successful.