Hello!
This recipe is VERY simple, but I think it's a fantastic idea for a snack or to have before exercising. I usually have this smoothie in the mornings before I go to exercise. That's why it's important to use non-dairy milk (like rice, almond, soy, etc.) because they are generally easier to digest and don't cause discomfort during physical activity.
I buy frozen fruit at the supermarket. They usually have strawberries, mango, blueberries, and mixed berries.