Two points here. First is Epictetus dichotomy of control: "We must make the best of those things that are in our power, and take the rest as nature gives us." So, we control our thoughts, responses, and actions. Everything else is out of our direct control. Secondly the concept of Fate Permitting i.e. we have a plan however we have no control over what other outside factors could change those plans. This requires one to be adaptable so that our own response is tempered to the situation and we don't "go all to pieces" whenever anything doesn't go as planned.