Stoicism begins in 3rd-century-BCE Athens with Zeno of Citium and reaches its great flowering under the Romans — seneca, Epictetus, Marcus Aurelius. It holds that a good life follows from a clear seeing of what is in our power (our judgments, intentions, actions) and what is not (everything else).
Its central practice is the discipline of assent — noticing the space between event and response, and choosing virtue there. Its aim is apatheia, freedom from the tyranny of the passions, and alignment with the logos, the rational order of things.
Stoicism has enjoyed a major revival in the 21st century as a practical philosophy, often rediscovered by those who came for ethics and stayed for the spiritual depth.