You have power over your mind \u2014 not outside events. Realize this, and you will find strength.\n\u2014Marcus Aurelius\n\nHaving a clear idea of what we can and can't control is the most fundamental principle of stoicism, and almost every other idea flows from there. This is also one of the easier concepts to understand, but so hard to actually implement.\n\nHow do you manage to clearly divide what you can and can't control?