If something in the future is cancelled or is about to be created, what is it? What is bound to happen, and how will it constitute us? Better yet, are we really concerned?
That's when we get anxious, knowing that anything could happen at anytime. But anxiety is nothing more than unconsciousness, an emotion that's there, but doesn't really do anything but hide the fact we might be invited to something delusional. Sometimes it clouds us with uncertainty, we just want to figure out a way to avoid the outcome. But how long though? Can we just ignore the possible outcome all together by focusing on another activity or a person until it comes back any time, or do we rush through and get it over with in hopes that everything will be okay afterwards?
As a man who has been living with anxiety for years, I would make plans and run conversations I want to say in my mind that would, in a sense and without any kind of perfection, match enough quality and intellect to the other individual, especially if it's someone very dear to me. But the one thing that everyone living with some sort of anxiety is that they never take care of themselves when going out into the world; not enough time to construct and abstract emotions and facts when looking at themselves in the mirror and asking, "Am I here right now?" "What's missing in me?" "Is this really going to happen to me?" This means that you will intellectually appreciate how irrational you are being; but you may still be (cognitively and biologically) disposed toward worrying.
The philosopher Epictetus admonishes you to stop trying to control things that are not under your control in the first place. If you can't beat them, then fuck it, it doesn't matter. Such probability estimates are all that you can rationally expect. So, in giving up your demand for certainty, and contenting yourself with what you can have, namely reasonable belief, you will have eliminated your perceived need to worry. My dad tried doing the same thing, but the funny life lesson he gave me, and still resonates with me greatly, is just sit back and watch other people struggle with their problems that you yourself cannot fix. For it is you that controls you and you can decide to sit front row seat to relax in and see it all or walk out and see another show.