A big part of relieving worry is accepting that no matter what you do bad things do and will happen. It all comes down to being comfortable with uncertainty.
There are many ways of doing this, but consciously recognizing it and labeling is as such then allowing yourself to be okay with the possibility of the bad thing happening.
If it is a big worry sometimes you need to make it as specific as possible. Like getting fired. What exact steps would happen? What would your boss say specifically? And is that exact scenario likely to happen?
If you're still having trouble do the above, but at the end change who its about, to a co-worker for example, then ask again is this a likely scenario. And if it is then the outcome won't be that bad. If it isn't then you also have your answer.
Another is to describe the worry in detail to another person because to describe it you need to make it specific and linearize it. This is why talking it/rubber ducking out works so well. They can also point out gaps and whatnot. Usually my the time your done the worry is gone.
Many friends feel like they're not actually helping here, but just listening is the help and it makes a big difference. On the flip side you may feel like you're wasting the other person’s time because at the end there's nothing to do. His is also false, most people are happy to help even if they don't know what they did.
Anxiety/worry usually comes from unexamined fears which throw every possible bad result into your head. But pinning down specific stories you can eliminate many of them.