If you don't add a liquid, you won't be able to blend your smoothie!
You can really have a lot of fun when it comes to choosing which liquid to add: milk, yogurt and water are classic choices, but why not switch it up and try coconut water, goat's milk, almond milk, rice milk, soy milk or even coconut milk! Add your liquid of choice slowly to the blender and mix little by little, until you reach your desired consistency.