One of the most simple and effective tools I have used in the past for neutralising internal anxiety is what I call 'conscious breathing'. This basically involves finding a quiet space where you won't be disturbed, followed by slow, deep inhaling/exhaling from your stomach region.
I say 'from your stomach', because it allows for expansion (ease), rather than contraction (stress). Many people nowadays, particularly ones that suffer from chronic stress and anxiety, tend to 'breathe' primarily from the upper areas of their chests.
Try it yourself - Take a few breathes from your upper chest, followed by a few breathes from your stomach. From my own experience, I have noticed incredible differences between the two, not only how it feels in my body, but the lasting effects it produces in doing so.
When you are 'breathing' from your upper chest, there is a feeling of contraction and 'fear'. In contrast, when you are breathing from your stomach region, there is a feeling of expansion, lightness and bliss which follows. Just listen to your body and follow what feels good!
Happy breathing!