The anxiety quote is one of the most famous quote in Stoicism and certainly the best anxiety quote by any philosophy or person. The quote was authored by Seneca the Younger who is one of the three key figures of Stoicism.
The quote has a longer version which is “There are more things, Lucilius, likely to frighten us than there are to crush us; we suffer more often in imagination than in reality.” which is part of the 13th letter of the Moral Epistles and Letters from a Stoic written by Seneca to his friend Lucilius.
The quote captures anxiety in one sentence what anxiety is really about – a series of problematic future events we envision that hinders our ability to enjoy the present moment. One of the most important thing to remember that almost everything we worry about the future, and proven by statistics, almost never happens. And even if that very small fraction of what we worry actually happens most of it are actually not that bad. The Stoics gives us a reminders to trust our ability to get through any challenges and by reminding us how many of the bad things in the past we have conquered and that if a real one really happens we are going to get through with it over and over again.