We can only see the future through the eyes of what we have seen before. I was amazed thinking about it a few days ago as I was reading a book in which a father spoke to his kids. I was wondering... how much will how you read the text be reflected by how you speak to the kids (and the voice you hear in the book). If you are used to hearing a yelling or complaining father, you might feel sentences from the father such as: "Throw the paper in the garbage" or "Go to bed" as threatening and loud words, while others might just like the sound of it and find the voice of the father to be a pleasing and enjoyable voice.
What do I mean? The way you actually hear the voice of the father in the book is very much reflected by the way you have heard your own father or the voices of other fathers or of yourself as a father. And that is what the quote is about... you will face your future with your past. You are brining all your luggage along, and your future will be understood in the light of your past.
That is why it can be useful to actually work on understanding your past, facing your demons from the past, and forgiving people who have hurt you in the past. Don't look at the future through the eyes of wounds and hurts. Of course, you cannot make the past change, but you can leave it behind and try to look at the future with new eyes and with grace and hope!