First, do you sit in a chair everyday for hours? How does your spine feel by the end of the day? Bad posture creates a lack of oxygen supply to the brain.
Sitting with a straight spine requires encaging the abdominals and breathing from the diaphragm.
In Kundalini Yoga we have a spinal flex series that addresses posture; and with sitting well comes a feeling of having more energy.
Second, when people breath from the mouth it only supplies the upper part of the lungs with air; which leads to a shallow breath.
In Kundalini Yoga many of the exercises require using the nostrils for breath.
Nostril breathing is vital for helping depression.
It is common to watch students leaving a Kundalini Yoga class looking "high on life" because of the breath work.
Third, our minds can be described as a computer chip that logs our past experiences and thoughts.
How do we clean that computer chip? In Kundalini Yoga we use all types of mantras to assist in re-programming how we think.
If a person is used to saying to themselves, "I am stupid" in a matter of time that is programmed into the brain and stored.
Depression is losing sight of your true self and believing false statements from the past.
In doing meditation work it not only cleans your computer chip, but also teaches the brain to be present.
Last, depression can become a habit of life.
By doing active scientific yoga movement you are forced to get out of the head and into the body.
In my many years of teaching I have discovered that the mind can easily lie, but our bodies will always lead us back to the truth.