The creative mind is capable of change. You don't just decide what you think at the outset and then go out and prove it. Instead, you start off with an idea and see if it works. If it doesn't, modify it, change it, reject it.
As you read, certain ideas will occur to you. You must learn to listen to them as they come up, distinguishing between what is interesting and what is not.
As I read poetry, I cannot not have ideas.