Without rest, we cannot be fully filled with God's love and grace in order to extend it to others. Both understanding the great need for rest and also the best way to rest personally is something God had been teaching me here in Greece.
We need rest because our Spirit needs to be strengthened. According to Psalm 23, God deeply desires to lead us to rest. He knows that the world, our flesh, and the daily struggles of this world can really weigh us down if we do not give them up to Him regularly. It seems very counterculture to rest, especially in a society where success is usually tied to the hardest workers, but I think this is a terrible reason not to rest. God's ways are usually not like this world. We need to be defined by His values, not the world's values. Even when He created, He made a point to rest when He finished. If our God, who is perfect and strong, finds rest important, how much more should we, who are imperfect and weak, find rest paramount.
Sometimes we know we greatly need rest, but we do not rest effectively or do not rest in the best way according to how God made us individually. Some people rest by spending time with people and just having a good time. Other people turn to music or reading or other hobbies. I have found that I must be alone in a place I know I will not be disturbed. I need to have honest and real conversation with my Best Friend and I must give my worries to Him. I am still learning how to make the most out of my time of rest, but I know God is faithful to show me and teach me how to rest well. I encourage any reader to do the same because strength and energy are incomplete and quickly drained when gained from worldly ways of rest.