Use frozen pineapple and spinach for a chilled, thick texture. Start with less spinach if new to green smoothies. Use a high-speed blender for a silky smooth texture. Add chia seeds, flaxseeds, or protein powder for extra nutrients. Substitute kiwis with green grapes, green apples, or pear if unavailable. Store leftovers in an airtight container in the refrigerator for up to 24 hours and shake before drinking.