The ancient Stoics produced a treasure trove of wisdom on becoming unconquerable. They believed that people cannot be conquered by anything external, as long as they don’t give away the power over their faculties.
The only way external things can influence us is when we, ourselves, let them.
If we feel that something has defeated us, it’s us defeating ourselves on account of it. If we want to become unconquerable, we don’t need to conquer the world but ourselves.
This video explores Stoic philosophy on how to become unconquerable.