From the 2013 Stoic Week Handbook:
Today’s Lunchtime Exercise: Stoic Acceptance & Stoic Action
One of the most fundamental ways in which Stoics achieved serenity was the practice of Stoic acceptance. Epictetus encapsulated this as follows:
Seek not for events to happen as you wish but rather wish for events to happen as they do and your life will go smoothly.
Epictetus, Handbook 8
This doesn't mean passively resigning yourself to events, though. It’s important to emphasize that Stoic acceptance primarily means recognizing that some things are outside of your control, and that if those events have actually happened, this must be acknowledged and accepted. However, you still try to do your best in responding to these events, for that is something which is under your control. Put another way: Stoic serenity comes from “accepting reality” or “accepting the facts” – but not giving up! It is about establishing a sense of purpose within the events of your life. The famous Serenity Prayer used by Alcoholics Anonymous provides a memorable summary of the Stoic doctrine:
God, grant me the Serenity to accept the things I cannot change;
Courage, to change the things I can;
And Wisdom to know the difference.
For example, there’s no point worrying about the past or the distant future, although of course we can learn from the past and prepare for the future. What’s beyond remedy is beyond regret. Stoics focus on acting with virtue in the “here and now”, insofar as that is within their sphere of control, from moment to moment. Practice the attitude of Stoic acceptance, therefore, during your morning and evening meditation, by reminding yourself to patiently accept the fact that it’s too late to change the past, and that the future may always turn out against your plans. Stoics desire only what it is within their power to change, which means desiring only to excel in terms of their character and conduct, while graciously accepting external events, even when they go against our plans or preferences. Throughout the day, as you bring your attention continually back to the distinction between what is under your control, and what is not, bear this in mind.
As we have just seen, whilst accepting there are some things we cannot change, the Stoics did focus on how you could act as well as possible in the things which are under your control. And in order to act as well as possible, the Stoic focussed on ensuring he was cultivating wise intentions for action. Marcus Aurelius said an intention should have three principal qualities:
1. It should be undertaken “with a reserve clause”, an attitude of somewhat detached “indifference” toward the actual outcome.
2. It should be “for the common welfare” of mankind, which perhaps comes closest to what we mean nowadays by saying that something is “ethical” – taking into account the well-being of others as well as our own, as if all of mankind were part of a single family.
3. It should be “according to nature”, meaning that some things are naturally worth pursuing and preferring over other things, both for ourselves and others, such as physical health, although these things are not considered intrinsically “good” in Stoic ethics.
Let's focus here particularly on the “reserve clause”. As we saw earlier, some people mistakenly assume that Stoics will be passive doormats, because they emphasize acceptance of external things. This should seem puzzling because history teaches us quite the opposite: that famous Stoics were often very brave, determined, and active in the world. The “reserve clause” allowed Stoics to reconcile action in the external world with a “philosophical attitude” of acceptance toward their fate. Put simply, it’s like qualifying every intention by saying “I will do such-and-such, if nothing prevents me” or “fate permitting”. Stoics aim to undertake every action with this in mind. They may begin each day, as this morning's passage from Marcus shows, by mentally rehearsing the many ways in which people and events could thwart their plans and preferences, while training themselves in serene acceptance, whether they meet with success or failure. And what is the Stoic aiming to do? As Marcus' key points show us, he wants to perform ethically sound actions for both oneself and others, cultivating positive states of mind, and obtaining positive 'externals' as far as possible, such as good friendships and a healthy body.
From now on during your morning meditation, you can practice incorporating the 'reserve clause', saying to yourself: “I will do xyz, fate permitting” or “if nothing prevents me” (or words to that effect). Imagine all the things that could go wrong, and rehearse an attitude of detached acceptance toward them, as if the only thing that really matters is that you “do your best” and that you intend to act wisely and virtuously. Do what you must; let happen what may.