This statement is actually rather simple. Your world consists of the people you allow into your life. The descisions you make. The risks you take. Your world is dependent upon every single thing you do. Your friends are apart of your world. Your family is apart of your world. That possible special someone is apart of your world. Your world is whatever you choose for it to be.
If you think about theme and understand what it is then you read the paragraph or sentence that you are reading then you will know exactly the theme of the story.