If you're worrying about something, one of two things is going on --
1. There's a good reason for your worries, they're justified, and you can potentially affect that outcome. If so, do something.
2. There's no good reason for your worries, they're not justified, or you can't affect the outcome. If so, stop worrying.
Easier said than done. But idle worrying does nothing of value. It makes you go crazy and doesn't make things better.
It's impossible to have perfect control of your thoughts, so worries emerge. When they do, investigate them, figure out if they're justified, figure out if you can do something, and then make a plan or let them go.