It is the end of an idiom for motivational speakers. Instead of shooting for the moon when pursuing life’s goals, researchers say people should be advised to aim a little lower if they want the best outcome. The tip may lack the punch of uncompromising drive, but aiming for merely above average tends to work out better, according to a mathematical model the team created to explore how ambition pans out. For those who want more mathematics in their lives, the model provides a guiding principle for situations as varied as knowing what salary to settle for and which flat to rent, to whether it is best to take the first parking space you find or hold out for a better one. It might even help in the dating game. Matt Burgess, an economist at the University of Wyoming, said the model provided a mathematical basis for conventional wisdom, with some important modifications.…