You Will Die - The fact that we are decaying things that die is the reference point for evaluating how we live a life. It should moderate ambitions, diminish self-importance, and have a liberating effect, as nothing you do is truly important.
To let go is the foundation of all practice. In essence, this means being able to let go of our beliefs, opinions, biases, theories, emotions, and desires in a timely manner. It requires that we are conscious of our inner states and that we know how to let go when we wish.