According to Yogic Science we have several layers (called the Pancha Kosha System) of being in which our consciousness operates. In plain terms this means there is more to experiencing human life and interacting with the environment as a human than just the physical body alone. According to the Pancha Kosha system we are operating in several aspects or layers of reality and each of these can be accessed if you have the right tools.
Within this Pancha Kosha system we have what is known as the Pranamaya Kosha or energy body which consists of our Chakras, Nadis, Auric Field and Vayus. Just as the other 5 koshas, without the energy body we would not be able to function as a human as it is vital to our life.
Breath is our access to the pranamaya kosha and this is why pranayama is very important to our experiential access to this part of who we are.
Imagine that if you stop breathing in 10 minutes you are dead (unless you are a yogi as you may be able to hold your breath longer than this and be ok).
Within the Pranamaya Kosha is the entire energy matrix of our body with different anatomical parts each functioning to achieve a purpose and that purpose is linked to keeping us alive and vital life energy flowing and maintaining optimal function of our existence.
These parts are: Chakras, Nadis, Vayus.
It is easy to understand these energetic concepts if you think of the analogy of cars on roads. Imagine the car is a unit of prana and all the cars in a city grid is the prana flowing through it. The cars use roads to get from one part of the city to the other in the same way your Nadis are the roads for prana to travel through your body and to get to its different parts.
The Chakras are like the roundabouts on the road, where different cars from different places in a certain section of the city can converge and go up the main avenue which in the energy body we call the Shushumna Nadi.
Some streets are one way, some streets are two way, so the direction the car can drive in a certain section of the road is like the Vayu which is a certain direction of flow.
Remember all these things are not physical but astral in nature and you cannot see them in a physical way. Although physical instruments cannot see them we can use our brain, senses and intuition because we are not just physical: we are also astral so we can use the astral parts of us to perceive these things.
Himalayan Kriya Yoga works with the energy body, fine tuning it and making it more efficient and free from stagnation, blockages and negativity.
Once this happens your entire life changes.