Juice half of a large red grapefruit and add 1/2 cup grapefruit juice to the blender. Now add the kale, apple, cucumber, celery, hulled hemp seeds, mango, mint, coconut oil, and ice. Blend on high until super smooth. (If using a Vitamix, use the tamper stick to push it down until it blends). You can add a bit of water if necessary to get it blending. Pour into a glass and enjoy immediately.