They say it's something that's better to learn sooner rather than later. I was never under the impression that life was fair but I learned how really unfair it was when I went on a secondary school trip with a few classmates to India.
One of them grew up in a lower middle class area and constantly complained about their parents never having enough money. Well when we arrived, it was a total shock to all of us. The amount of poverty there (homeless people, dirt, badly paved roads) was shocking. Nothing like one would see in Europe. That girl proclaimed after the trip that it had given her some perspective and she wouldn't be far more grateful.