Epictetus is harder — and more useful — than the internet slogan about control.
Use the Enchiridion and Discourses as training in judgment, responsibility and freedom rather than a list of detached quotes.
“Up to us” is about agency
The famous opening distinction points toward judgments, impulses, desires and aversions — the use of our own faculty of choice — rather than a generic productivity framework.
Influence is not ownership
You can prepare, persuade and work. The outcome still depends on causes beyond your choice. That distinction allows effort without making peace depend on possession of the result.
Read the Discourses too
The Enchiridion is compressed. The Discourses show the arguments and examples behind its sharp instructions.
Take one distinction from this page and apply it to one real situation before reading another article.
If you want to move from short Epictetus quotations to the Discourses and Handbook, start with a complete, readable edition. See the Stoic Library for edition notes and Amazon links.