“We control our reasoned choice and all acts that depend on that moral will. What’s not under our control are the body and any of its parts, our possessions, parents, siblings, children or country – anything with which we might associate.”
Epictetus, Discourses

The only thing in your control is your mind. That includes your attitudes, opinions, choices and will. Don’t sweat the small stuff. If your children are messing about and being unhelpful and rude, and your partner is grumpy after work, does it help to choose to react in a negatively-emotional way? You control what you decide to make of the situation.