For the overconfident

Cicero, On Duties, Book I, p. 36

...Men whom success has made unbridled and overconfident should be led into the training-ring of reason and learning, so that they perceive the frailty of human affairs and the variability of fortune.

To halt of our own accord

Seneca, On Tranquility of Mind, X 6:

Nothing can free us from these mental waverings so effectively as always to establish some limit to advancement and not leave to Fortune the decision of when it shall end, but halt of our own accord.

Foucault, The Care of the Self, p. 93:

And to Lucilius, who is not under any threat, however, Seneca gives the advice to disengage himself from his duties, gradually and at the right time, just as Epicurus counseled, so as to be able to place himself at his own disposal.

Armed with the virtue of fortitude

Why should I worry about what happens if I am armed with the virtue of fortitude? Nothing can trouble or upset me, or even seem annoying. Instead of meeting misfortune with groans and tears, I will call upon the faculty especially provided to deal with it.

'But my nose is running!' What do you have hands for, idiot, if not to wipe it?

'But how is it right that there be running noses in the first place?' Instead of thinking up protests, would not it be easier to just wipe your nose?

(Discourses, Book I, Chapter 6)

"The tyranny of fortune" - Descartes, sounding like Epictetus

As pointed out by Robert Dobbin, in his introduction to The Discourses and Selected Writings.

Rene Descartes:

I undertook to conquer myself rather than fortune, and to alter my desires rather than change the order of the world, and to accustom myself to believe that nothing is entirely in our power except our own thoughts...Here, I think, is the secret of those ancient philosophers who were able to free themselves from the tyranny of fortune, or, despite suffering and poverty, to rival the gods in happiness.