He means two things.
First, he means that we have to move from those episodes or things in the past that continue to hold us back. We have to “let go.” We have to keep our gaze toward the future rather than either clutching to the past in a nostalgic fashion or keeping in our mind the limiting thoughts and events that trap us there.
Haanel also means that we should begin as best as possible to trade the old for the new. If we want change for the better, we have to look around ourselves and find the things we can change now and then take action on them.
Here’s a practical way you can practice this as you master the mental aspects.
Look around your house and take notice of the things that could be replaced. Let us use as an example your drapes. If they are in need of replacing, then simply get rid of them! Do not sell them or try to make money from the transaction, merely give them to a charitable organization, such as The Salvation Army. By making the path clear for the better to enter, the better will arrive.
You can go even further and do a thorough house cleaning. This will unburden you of much of your baggage and clear the way for new and better things. It is not advocated to dispose of things of value, but the general rule is that if you haven’t looked at a thing in many years, then it can go.
Both mentally and physically.
These books are great because they are already clean.