A lizard never thinks something is wrong with the world, even as it watches its young get eaten alive. It doesn't tell itself "something is wrong with the world," because it doesn't have enough neurons to imagine the world being other than what it is. It doesn't expect a world in which there is no predators, so it doesn't condemn the world for falling short of expectations. it doesn't condemn itself for failing to keep its offspring alive. Humans expect more, and we do something about it. That's why we end up focused on our disappointments instead of saluting our accomplishments.
Loretta Graziano Breuning, Habits of a Happy Brain: Retrain Your Brain to Boost Your Serotonin, Dopamine, Oxytocin,  Endorphin Levels
brain, neuroscience, psychology