Our blood is controlling the energy in our body . Normally, when we’re not in fear, the blood is more or less concentrated in the organs that actually help the body grow and repair itself and maintain itself. However, if we live in fear or we are stressed the adrenal system is going to redirect the blood flow into the arms and legs because those are the organs that we use to escape the fear. That is called the fight-or-flight response of our body.

So when you’re living in fear or stressed, you shut down the growth and maintenance of the body as you prepare for fight-or-flight. And there’s another effect as well. That is when fear hormones are put in the body,we want to conserve all the energy possible to run away from that threat. This is particularly important in regard to the immune system. The immune system is like an internal adrenal system. The immune system protects you from threats on the inside. The immune system uses a lot of energy. You know that, because if you’ve ever been sick, you realize how little energy you have. You may not even have enough energy to get out of bed. So, the significance here is important. When the stress hormones are released in the body to conserve the energy for fight-or-flight, the stress hormones shut down the immune system. And this is very vital because the usage of that energy by the immune system is so high, it would interfere with the fight-or-flight response. Not only do we redirect the flow of blood away from the vital organs, which maintain our body, we also inhibit the immune system, which is protecting the cells in our body.

So when you are stressed over a longer period, you are "killing" your immune system and your cells, which will cause physical illness.