They worry about the future envisioning something happening that is remotely possible and replaying the scene over and over their head until said event actually does happen.
Or regurgitating bad memories up in your head and replaying those things that you didn’t like the first time it happened yet somehow your brain keeps on bringing them up.
See that is time travel, too. Traveling in your mind. Not on purpose, but it happens.
That is what your brain does to keep itself busy.
But you can stop it. By being aware of it.
So the next time you are thinking about something bad that happened in your past or worrying about something that ‘could’ happen in your future, remember that is just a thought. Its not real.
And you can have control if you want it.