Breath is life. Meditating upon its presence is meditating upon our lives. It is the now, the present as it is. We can apply the skill in almost all the things we do daily. As soon as we bring our attention to the breath, the great power of observation comes to us naturally.
Meditation is an advanced and delicate practice. When the mental fluctuations cease abruptly, the subconscious could emerge. The sudden shift could result in the withdrawal the physical energy. This shall trigger the nervous system to increase heat, causing high electrical loads in the nerves and skin. The heart and the lungs could stop due to this. The effects on consciousness can be detrimental if one is not careful.