The brain is a very complex piece of natural machinery. It billions of neural connections, and is what gives us the capacity to not only achieve great feats of ingenuity and experiment, but also to experience a gamut of emotion. This range of emotion will take in less comfortable metal states, such as anxiety.
It happens to all of us at some stage, and it is the way we deal with it that matters. Mindfulness has proved for many people a good technique to ease anxiety, and this article attempts to explain the neuro-scientific reasons why that is.