I will give them an undivided heart and put a new spirit in them; I will remove from them their heart of stone and give them a heart of flesh.
Are you able to identify what kind of heart we have? Heart of stone or heart of flesh. Stone means hard and flesh means soft.
Imagine a potter taking some clay. What will he do if the clay is hard and not moldable? He may press it hard and do whatever it takes to make it soft. This is because he wanted to shape that clay into a beautiful, useful object.
What if the clay has lots of stones in it? He may throw it aside. God being the potter he doesn't want to throw us aside. He can give a heart of flesh.
What are few stones in our heart which is hard to break, may be our sins, some traditions, some convictions, some relationships? Pray for God to replace them and make our heart moldable.