Dear tj123,

There is no "right" answer or preferred topic to write about by the admissions committee. Successful applicants have written about personal aspects of their lives as well as professional. Some have even written essays that cover all aspects of their lives where something like integrity is what matters most. What the admissions committee is looking for in this question is insight into who you are and what motivates you. Topics can range from personal history to grand visions of the future. Be sure to include specific examples which show you have demonstrated or experienced "what matters most" throughout your life. If you are able to do that, then you will have thoroughly answered the question.

Good luck,
Lisa