Drawing lines is about living a righteous life, not limiting people or circumstances. When we embrace that idea, we are able to set out on a new path.
God established the principles by which life and relationships operate. Often we live ignorant of these principles and experience unnecessary difficulties.
As we learn to draw healthy lines within our limits, we quickly discover that it is Love that drives this process. So first we learn to Love God and allow His Love to draw the lines within us.