Mindfulness is only actively choosing what you're paying attention to. Mindfulness meditation is the exercise of picking something to pay attention to, and then continually bringing your attention back to it whenever you find your mind had wandered. Practicing this 10 minutes per day strengthens your ability to recognize and choose where your attention goes.

Anxiety at a cognitive level is caused by your mind thinking about things in the past or the future that are not serving you well. Strengthening your mindfulness skills allows you to recognize when your mind has wandered into that territory and decide to let it go and give your attention to something else.

Unfortunately our modern society is designed in a way that encouraged shorter attention spans and less control over our attention

I’m no expert myself, but what it definitely can do is help you recognize the different symptoms that you can feel in your body that your brain recognizes as anxiety, that way you can kind of break the cycle of the body influencing the mind and vice versa. Then there is non-identification, which means that you kind of look at your anxious feelings, as if you are a spectator, not identifying with them. This way you realize you are not your feelings, but you have your feelings and can snap out of them way quicker and not get caught in a loop. It sounds kind of trivial when talking about it, but experiencing it can be quite profound.