Stoicism, as understood by Marcus Aurelius and fellow ancient philosophers Epictetus and Seneca, is something far more demanding and far more useful. Its foundational insight is deceptively simple: there are things within your control and things that are not, and conflating the two is the source of most bad decisions. You cannot control the weather, the behaviour of others, or the hand that fate deals you. You can control how you respond, what you build, and whether you do the work that is yours to do. The stoic doesn’t retreat from the world and accept whatever fate throws at him with passive indifference. The stoic acts in a composed and reasoned way, but focuses on action and what he can actually change.