research in cognitive psychology shows that we cannot perceive anything without contrast. That is, you can see a black line on a white piece of paper, but not a black line on a black piece of paper. The same is true of all types of perception, thus emotional conditions also require contrast. A good day feels great because some days are not so good. Joy derives meaning from sadness. It is the differences in life that make you notice. You need all of your experiences in order to fully experience the positive ones!
