Let go of the past. We must only begin.

From The Daily Stoic by Ryan Holiday and Stephen Hanselman. 

I am your teacher and you are learning in my school. My aim is to bring you to completion, unhindered, free from compulsive behavior, unrestrained, without shame, free, flourishing, and happy, looking to God in things great and small—your aim is to learn and diligently practice all these things. Why then don’t you complete the work, if you have the right aim and I have both the right aim and right preparation? What is missing? . . . The work is quite feasible, and is the only thing in our power. . . . Let go of the past. We must only begin. Believe me and you will see.

—EPICTETUS, DISCOURSES, 2.19.29–34