How well do you know your instructors who create the exam. If you know them you usually know what they want to teach you. Clues are in their lectures or you can ask them.
When you know that a purpose of to know what the book is aiming to teach me so that I can pass the exam with my best passing grade becomes workable. And is your primary purpose or current goal in life. As a motivator the purpose is weak.
Don't confuse purpose with questions. When you start looking at a book and saying I need to know this, and that and understand this, You're heading into the direction of mind probing questions. Write down the questions. That starts filling your purpose of knowing what you consciously need to know to pass the exam.
Remember to mind map if it's important to you to know the stuff.
AlexK
