6 ideas
Emotional suffering is driven mainly by our judgments about events, not by the events themselves, following Epictetus's line that people are disturbed by their opinions of things. Changing those judgments therefore changes the emotion. Albert Ellis and Aaron Beck both credited this Stoic idea as the foundation of cognitive therapy, which makes CBT a modern recovery of ancient philosophical practice.
Split every situation into what is up to you (your judgments, intentions and responses) and what is not (outcomes, other people, your body, your reputation). Put all your effort and concern into the first category and accept the second calmly. Anxiety comes largely from trying to control the second.
James Stockdale was a US pilot shot down over Vietnam and held for more than seven years as a prisoner of war, where he was tortured. He relied on Epictetus's teachings to decide what remained under his control: his will, his conduct and his refusal to be broken. He treated the rest as outside himself, which kept his integrity intact under conditions designed to destroy it.
Knowing a true principle is not enough, because under stress people fall back on automatic, habitual reactions. Ancient schools therefore drilled their ideas through repetition: memorised maxims, personal notebooks, and daily morning and evening reviews. The aim was for wise responses to become as automatic as the old, damaging ones, which is the same logic as CBT homework.
Imagine looking down on your situation from a great height, where your life shrinks to a tiny point in a vast cosmos and a brief stretch of time. Seen at that scale, your worries, grudges and craving for status lose their grip. The shift in scale restores proportion without denying that the problems are real.
When governments and institutions adopt CBT-style resilience training, they tend to strip out the ancient question of what a good life actually is. That leaves a technique for adjusting people to whatever goals the state or employer sets. The ancient schools paired emotional techniques with open, Socratic inquiry into values, and that pairing keeps self-help from becoming compliance.