Success is going from failure to failure without a loss of enthusiasm.

"It is most gratifying," it said, "that your enthusiasm for our planet continues unabated, and so we would like to assure you that the guided missiles currently converging with your ship are part of a special service we extend to all of our most enthusiastic clients, and the fully armed nuclear warheads are of course merely a courtesy detail. We look forward to your custom in future lives ... thank you."

Nothing great was ever achieved without enthusiasm.