We are ruled by our emotions, and there is really only one way of ruling them back, and that's to be aware of them.
This exercise is a quick and easy one that you can throw in between your daily tasks any day of the week. It belongs to the water-element, and gives you a solid awareness of your emotions. A key component for a writer.
By practising it regularly you will begin to see a pattern in your emotional behaviour, and it will help mature your voice.