"It is not circumstances themselves that trouble people, but their judgments about those circumstances. For example, death is nothing terrible, for if it were, it would have appeared so to Socrates; but having the opinion that death is terrible, this is what is terrible. Therefore, whenever we are hindered or troubled or distressed, let us not blame others, but ourselves, that is, our own judgments. The uneducated person blames others for their failures; those who have just begun to be instructed blame themselves; those whose learning is complete blame neither others nor themselves."
-Ch. 5 of Epictetus' Handbook
Measuring progress in a lived philosophy isn't necessarily simple. Stoicism is meant to establish a "good flow of life" in its adherents. For instance, a person who is living well will be calm in the face of adversity, if not joyful. They will also use their skills to benefit their community, and seek to expand the very idea of community as wide as possible. The impact of lived Stoicism should be apparent to all but, because of its holistic nature, can sometimes be difficult to point out, even to ourselves. We are often more comfortable with a simple checklist.
Unfortunately, when something can be itemized, it's often not very useful as a measure of progress. It is far too easy to turn to false indicators (number of books read, quotes memorized, or arguments won) as a gauge of success. Even a positive indicator can be misleading. I may maintain a calm demeanor all day, not because I stoically accept the world warts and all, but because I wasn't faced with any potential obstacles to my tranquility. Thankfully, every once in a while an ancient Stoic points to an indicator that is hard to fake.
The uneducated person blames others for their failures; those who have just begun to be instructed blame themselves; those whose learning is complete blame neither others nor themselves.Epictetus says that Stoics blame themselves for moral failures. That's pretty cut and dried. As long as I am honest with myself, I can review my weak moments and see who or what I blamed. Did I claim that, "the traffic made me angry"? Was my co-worker, "so frustrating"? If so, I wasn't approaching those events as a Stoic. If I instead told myself, "I shouldn't have become angry today in traffic," or,"why did I decide to frustrate myself just because Jake can't do his job," then I messed up in the moment, but I recovered. Taking the blame is, in itself, a sign of progress. If I go a step further and avoid any anger and frustration in the first place, all the better! By the way, Stoics don't blame themselves for the events that are happening to them. Traffic isn't my fault. We do, however, accept control over our reaction to life. Our reactions, based in our judgement of the situation, are firmly in the moral sphere.
So if you're trying to live the Stoic life, where are you placing blame? Epictetus says it's all on you. If you're like me, you might prefer to skip the blame game and move on to living blamelessly, but let's face it, that's not going to happen. It is not circumstances themselves that trouble people, but their judgments about those circumstances. That is a fundamental truth of our philosophy. It takes daily work to internalize it. If we don't, we won't have a good flow of life, and there will be no one to blame but ourselves.