Anxiety is a tricky thing. It's such an un-agreeable feeling that if you don't keep it in check you can begin to become anxious about being anxious. You start avoid scenarios not because you necessarily fear something specific, but because you're worried something might make you anxious. This in turn makes you more anxious. Objectively, this is, as you say, irrational. You're inflicting self-detriment over self-created hypotheticals. Kind of like creating an invention in your head then being annoyed it doesn't have a certain feature.

On examination of my own anxiety through mediation, I found it all stemmed from an avoidance of being in the moment. Any situation which meant I hadn't had a chance to think about or pre-empt it somewhat left me uneasy. Any scenario where the outcome meant that I would have to figure things out on the fly I avoided. With continuing practice, I have learnt to see thoughts as they are. Transient electronic signals in the brain. Ones that can only last and strengthen as long as I dwell on them. Letting them go is a simple as objectively acknowledging them and then choosing not to give them any more attention.

The best essences of life lie in those times of being in the moment and riding the wave, dancing the dance. See yourself not as a slave to your thoughts. You are always in control. Of course, this is easier said than done and it's no flick of a switch. But with sustained mindfulness practice I all but guarantee you will see improvements in relation to your anxieties.