Why do you read a book? What do you want to get from a book - that's your purpose. You can have multiple purposes, they can also change.

Questions, just write down what comes to you? Make up a question that you think the book should hold an answer for.

Activation, try all the methods. How do you expect activation to work? If you find the answer to your questions, that is activation. If you draw a summary of a book, that's activation.