A key argument of the Stoic philosophers is to separate what is in our control and what is outside of our control. The thoughts of other people, for example, are outside of our control. Our words that we choose - which may, of course, influence those thoughts, are inside our control. To focus, for example, on the thoughts of others is to weaken our reasoning power; to focus instead, on our own persuasive abilities is to strengthen our power.
Pierre Hadot, the French historian of philosophy, calls this "discipline" or practice of sorting out what is in and outside of our power the "Discipline of Desire." Desire, in this sense, means our passions - the passive elements of our lived experience, in which forces external to our consciousness incite, press upon and move us - hence making us passive before them. The active part of our life flows from our consciousness.
Hadot cites many examples in his book The Inner Citadel of Marcus Aurelius practicing the Discipline of Desire. Marcus Aurelius writes, for example, "He who separates and distances himself from the Reason of common Nature, and complains about what happens to him, is an abscess upon the world..." (IV, 29, 2). Marcus argues that, once we separate what is in and outside of our control, it is irrational to complain about that which is outside.
The discipline of recognizing this separation frees us to dedicate our power to those elements which are in our control: our thoughts about the world, which in turn shape our words, our actions and our characters. We all know people who waste their power on complaining about the world around them. (We all know that we, too, often act this way). Marcus Aurelius describes this freedom, "You will open up a vast field for yourself as you embrace the totality of the cosmos in your thought, conceive everlasting eternity, and consider the rapid metamorphosis of each individual thing." (IX, 32).
Part of this freedom stems, ironically, from recognizing how little is actually within our control. Marcus Aurelius frequently writes about the vast amount of the universe which is operating completely independently of us. He writes about our small part of time, matter, soul and patch of earth that we inhabit and control. "What a tiny part of the infinite time is assigned to each one of us! For it disappears so quickly into the everlasting. What a tiny portion of universal substance, what a tiny part of the universal soul! On how tiny a part of the entire earth do you crawl!" (XII, 32). Elsewhere he writes, "Asia and Europe are corners of the world. The sea is a drop of the world. Athos is a lump of earth, and all present time is a point within infinity. Everything is tiny and unstable, and everything vanishes (in immensity)" (VI, 36). We waste energy thinking of many outside-of-our-control experiences as big, terrible and dramatic. By recognizing, through a kind of hyerbole, how tiny our vexations are, how much lies outside of our control, we ironically free more of our internal resources for those elements which we do control.
The Stoic Discipline of Desire goes even further. The Stoics ask the question, what is the wise attitude toward these elements outside of our control? Their answer is, in a sense, love. Since all these events are outside our control, the wise response is to love them as the gifts of Nature. Any other response to events outside our control is irrational and counterproductive: inducing passions - passions which weaken our active powers and make us more passive. Hadot draws inspiration from a Nietzschian phrase to entitle this capacity Amor Fati or, the Love of Fate. He summarizes the outcome of this ancient discipline: "The result of the discipline of desire... was to bring people inner serenity and peace of mind, since it consisted in the joyful consent to everything that happens to us through the agency of universal Nature and Reason. Amor Fati, or the love of fate, thus led us to want that which the cosmos wants, to want what happens, and to want what happens to us" (The Inner Citadel, Chapter 8, "The Discipline of Action, or Action in the Service of Mankind").