God is constantly molding & mixing us but we keep throwing in things, impurities, that don't belong (lies, etc). The longer those things stay in the concrete the harder it is to remove them. When we/God do(es) remove them, sometimes they have to be broken off.
Sometimes the things we add are just flecks, almost like glitter, that are buried deep down that we think add beauty but are actually detrimental to the integrity of the strength of the concrete. Sometimes, because they are buried so deep or are mixed in so well, we don't even see them or know they exist.
What have you been adding to your life that doesn't belong, that God hasn't given you?
What do you need to get rid of to allow Him to fully reside in your life?
Ask Him to show you the areas of your life that you have been hiding away and allow Him to cleanse those for you.