A large part of parenting is about managing weariness and motivation. Much of the success of parenting is about avoiding the sins of "omission" as well as "commission." You can feed, clothe, and house your kids and not really parent them. When we raise kids for selfish reasons (to feel proud, to have people love us and appreciate us), if they disappoint us we'll pull back. But when we realize that God has called us to raise godly children and God is always worthy to be obeyed, we have a motivation that goes beyond our own pride and our own comfort.