It is best to do this exercise in a quiet place

There is no right or wrong way to carry out the
visualization. Be intuitive with it and do not feel you are
unable to carry it out if you feel you are not very good at
seeing mental imagery. As long as your attention is on the
exercise, you will gain benefit.
It is best to do this exercise in a quiet place where you
won’t be disturbed, and then when you are more practiced
you will be able to get the same positive results in a busier
environment such as the workplace. You should notice a
calming effect on your state of mind along with a sensation
of mental release and relaxation.
Either sitting or standing, close your eyes and move
your attention to your breath. To become aware of your
breathing, place one hand on your upper chest and one on
your stomach. Take a breath and let your stomach swell
forward as you breathe in and fall back gently as you
breathe out. Take the same depth of breath each time and
try to get a steady rhythm going.
Your hand on your chest should have little or no
movement. Again, try to take the same depth of breath
each time you breathe in. This is called Diaphragmatic
Breathing.
When you feel comfortable with this technique, try to
slow your breathing rate down by instituting a short pause
after you have breathed out and before you breathe in
again. Initially, it may feel as though you are not getting
enough air in, but with regular practice this slower rate will
soon start to feel comfortable.
It is often helpful to develop a cycle where you count to
three when you breathe in, pause, and then count to three
when you breathe out (or 2, or 4—hatever is comfortable
for you). This will also help you focus on your breathing
without any other thoughts coming into your mind.