Two comments from Epictetus

The chief task in life is simply this:  to identify and separate matters so that I can clearly to myself which are externals not under my control, and which have to do with the choices I actually control.  Where then do I look for good and evil?  Not to uncontrollable externals, but within myself, to the choices that are my own...

. . .

These things don't go together.  You must be a unified human being, either good or bad.  You must diligently work either on your own reasoning or on things out of your control - take great care with the inside and not what's outside, which is to say, stand with the philosopher, or else with the mob!

(link)