Anxiety is created by three sources: those things over which we have no control, those things over which we do have control, and those things over which we should have control.
The anxiety caused by things over which we have no control is nonsensical. If there’s nothing we can do about a circumstance, there’s no need to worry. And if God orders the universe, then uncontrollable circumstances are opportunities to exhibit and cultivate virtue.
The other two anxieties, those caused by what we control and what we should control, require immediate action. They are perpetuated by timidity or laziness.
If we already have control in a particular situation, but we have not taken action, we are governed by fear. We are afraid to do what is required of us. In which case, we must rally under the banner of "Do It Now". Much of our anxiety would be absolutely eradicated if we simply did small things now rather than letting them (and our fear about resolving them) grow.
In some cases, anxiety is caused by having the capacity for controlling the situation, but not having the competence. This kind of anxiety is the sort that makes you imagine or replay embarrassing or dangerous situations in your head, thinking through all the probabilities and possibilities.
It’s your mind begging you to obtain competence. In which case, the answer is also "Do It Now". Learn what you need to learn, acquire the skill you need to acquire, practice what you need to practice so that competence outweighs anxiety and you feel that you can confidently approach that situation if it presented itself.
If you imagine and replay embarrassing and dangerous situations in your mind but do nothing to address them, then you’re cultivating neuroticism and you’re making yourself less useful. Soon you’ll be a victim.
If there’s nothing you can do, accept it well. If there’s something you can do, do it now.