Sheep need a lot of management. The shepherd has to make sure to keep them moving around to avoid overgrazing in one area. Overgrazing an area can not only lead to a lack of pasture, but can also foster the growth of parasites. However, sheep can also be very stubborn and not want to move from an area where they are comfortable. They have to be prodded by the Shepherd to move on to better pastures. Jesus, the Great Shepherd, encourages His sheep (us) to move on, to get out of their comfort zone, and to not hold on to things that are parasitic in their lives. Like sheep, we are often stubborn and need gentle (or not so gentle) prodding. (Psalm 23:3b NKJV)