When we come out of the womb and take our first inhale and when we pass away and take our last exhale the breath is primal and fundamental to are being.
Since breathing is something we can control and regulate, it is a useful tool for achieving a relaxed and clear state of mind. Here are some simple breathing exercises:
Exhale completely through your mouth, making a whoosh sound.

Close your mouth and inhale quietly through your nose to a mental count of four.
Hold your breath for a count of seven.
Exhale completely through your mouth, making a whoosh sound to a count of eight.
This is one breath. Now inhale again and repeat the cycle three more times for a total of four breaths.
Place one hand on your chest and the other on your abdomen. When you take a deep breath in, the hand on the abdomen should rise higher than the one on the chest. This insures that the diaphragm is pulling air into the bases of the lungs.
After exhaling through the mouth, take a slow deep breath in through your nose imagining that you are sucking in all the air in the room and hold it for a count of 7 (or as long as you are able, not exceeding 7)
Slowly exhale through your mouth for a count of 8. As all the air is released with relaxation, gently contract your abdominal muscles to completely evacuate the remaining air from the lungs. It is important to remember that we deepen respirations not by inhaling more air but through completely exhaling it.
Repeat the cycle four more times for a total of 5 deep breaths and try to breathe at a rate of one breath every 10 seconds (or 6 breaths per minute). At this rate our heart rate variability increases which has a positive effect on cardiac health.
Once you feel comfortable with the above technique, you may want to incorporate words that can enhance the exercise. Examples would be to say to yourself the word, relaxation (with inhalation) and stress or anger (with exhalation). The idea being to bring in the feeling/emotion you want with inhalation and release those you don’t want with exhalation.
In general, exhalation should be twice as long as inhalation. The use of the hands on the chest and abdomen are only needed to help you train your breathing. Once you feel comfortable with your ability to breathe into the abdomen, they are no longer needed.