Your presence here on earth depends upon being in a body. In terms of the four lower bodies, your physical body is the most important element even though each of us want balance between all four lower bodies.
Your negative thoughts, or negative view of life also wear down your etheric body, which is the closest to your physical body. This may lead to poor energy or fatigue or worse, illness. Many of us have carried multiple behaviors from one lifetime to another.
The four lower bodies are light vehicles that have consciousness and are directly related to your consciousness. They do not lead, but reflect the experiences that you take in. Therefore, they are receptors and warehouses for information collected from human experiences.