They focus on what is in their control and strive to accept what is not in their control.
From the Serenity Prayer:
God, grant me the serenity to accept the things in cannot change
The courage to Change the things in can
And the wisdom to know the difference.
You can’t choose your parents or the weather. But you can choose to have a drink or not.
The Stoics have a saying
“Ta eph’hemin, ta ouk eph’hemin”
“And what is up to us?”
What is up to us is
The rest is not in our control and all effort spent worrying about it is wasted.