Diligence is important but other important qualities are needed as well. Other qualities include: planning, learning from one's mistakes, and avoiding procrastination are important factors in success. Without these other qualities, a person with diligence can only go so far. One must not only work hard but work smart on the path to success.
Smart work leads to nowhere. Of Course diligence has its importance, but other qualities are needed for success and excellence. Proper planning, covering what is most important first, judging and deciding what is to be done when, and avoiding procrastination is the perfect path to success. All the very best!!