It is okay to brag a bit when answering this question. Showcasing your pride in your career accomplishments will clue them into your experience level and your level of enthusiasm for the work you perform. The most successful career-minded individuals are those who love what they do. So, sharing the accomplishments you're proud of will clue them into your values, personality, motivators, and how to coach you in the future. Your answer will reveal why you're proud of the example you provided and how it fits into your career goals. It will also reveal more about your personality and how you like to be motivated, indicating how to coach you in the future.