There are only three kinds of business: your own business, someone else’s business and Hashem’s business.
Stress arises when we get into someone else’s or Hashem’s business. You can’t control an earthquake or a virus. Similarly, you can’t control someone else’s words or actions.
It is not that you can’t be concerned or disappointed about things beyond your own business. Just recognize that those are really outside your circle of control, and adapt the time and brainspace you allocate for those accordingly.
If you do get into the space of the others’ business you will end up spinning your wheels thinking and ruminating about how things should be different than they are. And that’s when the stress and suffering happen.
Mind your own business. It’s the only place where you have control and can make a change.