You know those thoughts you get mostly when something negative is already happening and you start getting ideas worse than what is actually happening and you freak yourself out and possibly get depressed?
We all did that sometime in our life before. These thoughts sometimes even come to us when we are perfectly fine and nothing is wrong with our atmosphere. But the key here is to not react to those thoughts as if they are actually happening.
The key is to acknowledge that they are not true and are not in your reality and just in the theater of your mind.
Let these thoughts pass, don't react to them, and don't believe them. Our brains are complicated, they are sensitive and sometimes super weird.
One mental exercise that can help you is thinking of a dry erase board that gets filled up with these thoughts when you start wondering and then when you want to silent them, imagine yourself getting an eraser and wiping them all.
Remember not to be the prisoner of your own thoughts.