Nostalgia. It's a powerful thing. All of us have experiences in our life that we look back on with something beyond fondness, often wishing, sometimes desperately, that we could go back and relive those moments. Numerous scientific studies have shown that the mind tends to amplify happy moments into something far larger than the actual events. So in that vein, nostalgia tends to work as a reward system for the brain. Happiness is a natural state for human beings. We want to be happy and, when we take part in experiences that make us happy, our brain loves revisiting and magnifying those times so that it can be made happy again.