The lives of all beings are marked by three characteristics: impermanence, egolessness and suffering or dissatisfaction. Recognizing these qualities to be real and true in our experience helps us relax with things as they are. The first mark is impermanence. That nothing is static or fixed, that all is fleeting and changing, is the first mark of existence. We dont have to be mystics or physicists to know this. Yet at the level of personal experience, we resist this basic fact. It means that life is not always going to go our way. It means there’s loss as well as gain. and we don’t like that. 

Pema Chodron, Comfortable with Uncertainty