Glenn E. answered 12d
Admissions Leader Specializing in College Essays and Writing
The first thing I advise students to do is to think about what matters to you. What was important, exciting, profound in some way. Them relate it to the question at hand. It may sound a bit cheesy, but as someone who has reviewed several thousand essays in their career and reviews nearly a thousand yearly - you can typically tell when the theme has genuine meaning to the student. Plus, it's more fun to write about something that is meaningful and exciting.
I also think something that tends to get overlooked is aligning how you process information with how you approach brainstorming your essay. For example - are you a verbal processor and want to record yourself for a minute or two discussing why the topic is important? Or, do you prefer to reflect and think deeply and journal some ideas first.
Think back to some of the essays or papers you are most proud of and received the best grade. What did you do to create that paper? What was it that inspired you to create a high quality piece of work? Then, you can reverse engineer some of the circumstances/approach for your college essay.