You have power over your mind - not outside events. Realize this, and you will find strength - Marcus Aurelius.

The dichotomy of control is a Stoic practice that, in essence, states that some things are within our control, while others are not. What is in our control is extremely limited compared to that which is out of our control. These are our mental faculties, desires, and our actions, among a few others. Outside of our control is our health, wealth, and how others see us in the world. While we can have influence over the aforementioned uncontrollable things, we in no way have complete control over them. 

This may sound incredibly easy, but it is profoundly difficult to put into practice, as you must accept how little is truly within your control, and practice the dichotomy of control almost religiously in your daily life, but it gets easier.

Modern Stoic writers have attempted to make the dichotomy of control into a trichotomy of control, but this is falling into the exact disease of the mind Epictetus warned us about through his Discourses, saying:

‘Your desires are inflamed, your aversions are low, your purposes are inconsistent, your motives are out of harmony with nature, your opinions are ill-considered and mistaken’ 

This is the disease of modernity, wherein we desire instant gratification out of everything else, especially if we can do it with minimal effort, rather than taking control of our own psychological angst, leading to a state of equanimity.