Nowadays, we use the term stoic to describe a person who can endure pain or hardship without showing their feelings or complaining. Nevertheless, to be stoic is beyond being emotionless.
Stoicism is an ancient school of philosophy founded by Zeno of Citium in Athens in the early third century BCE. It flourished during the Hellenistic Era due to its effectiveness. Furthermore, it was practiced by people of many different social statuses, including Marcus Aurelius, a famed Roman Emperor; Epictetus, a former slave; and Seneca the Younger, a famed playwright and tutor to Emperor Nero.
(From left to right: Marcus Aurelius, Epictetus, Seneca the Younger)
Like many Hellenistic philosophies, stoicism celebrates the four cardinal virtues: wisdom, courage, temperance, and justice. Perhaps stoicism can be best encapsulated in three dimensions:
Perception: the objective judgment now at this very moment
Action: unselfish efforts you take
Will: willing acceptance and endurance of the challenges of life
Indeed, stoics do not ask why things happen to them; stoics only respond virtuously to them.
To learn more about stoicism, check out this video, Letters by Seneca the Younger, Meditation by Marcus Aurelius, and subscribe to The Daily Stoic founded by Ryan Holiday.