This is a personal question. Therefore, no one can answer it except for you. However, there are some steps that might help you get started with the topic.
First, you should have a clear idea in your mind of what Indiana University would allow you to achieve. In order to know this, you need to spend some time researching the institution. In order to talk about your academic goals, you should think of the subjects that interest you and that you would most likely pursue in college. On the other hand, if you want to talk about your career plans, think about the ways in which such classes would relate to your future plans.
When it comes to unusual circumstances or challenges that you faced when pursuing your education, you should focus on obstacles that you have found in the past. These can include problems with your family, insecurities, economic issues, or any other similar topic. Make sure that when talking about this subjects, you are clear about the way in which these obstacles impacted your pursuit of education.