This is something I use:

When a fearful thought comes to mind.

Before you would react with anxiety try to force that thought out of your mind.

This time, however, say:

“That’s a fear of X. I could worry and even obsess over that but this time I’m going to do something different.

I’m not going to react to it. I’m also not going to try and stop it either. I’m just going to label the thought and not react.”

Then the thought comes again with more intensity and possibly with new ‘scary’ angles you never considered.

When this happens you do exactly the same. As if you were observing a cloud passing overhead, you simply

-Observe it,

-Label it e.g (this is a fear of crowds)

-Watch it as it passes by with no judgment.

then

-Continue your attention on to what you were doing.

Observe, Label, Watch, Continue

If you are a more indoors type of person then instead of thinking of the thoughts like clouds passing in the sky, you might try imagining a large cinema screen and the anxious thoughts are projected out onto the screen in front of you. Play around with this approach. Find what works for you.