Answer: Just as the body is energised by the physical food that you take, the mind is energised by the breath. The kind of breathing you do will affect your mind. When you are angry or excited, you tend to breathe very fast. When you are calm, your breathing is slow and steady. Therefore, the mind can be controlled using the breath.
If you have too many fickle thoughts coming and disturbing you, start breathing very deeply. Slow down your breathing. By slowing down your breathing, you are not giving enough energy to the mind to keep moving this way or that way. Without the energy, it will slowly settle down. Once it settles down, things will be clearer. Therefore, practise deep, long breathing.
In the initial days of practice, people will inhale and exhale quickly because they do not have the capacity to hold; but, with practice, you will get better at it. Inhale for a duration, hold for the same length of time, and exhale for the same duration – this is the right method. Eventually, the duration of holding your breath should grow longer, and the inhalation and exhalation should reduce.