From this post on Open Loops:
Our autonomic nervous system controls the systems of the body that we don’t think about, including our heart beat/rate, respiration, and digestion. The autonomic nervous system is made up of the sympathetic and parasympathetic nervous systems. When the parasympathetic nervous system is active, it, among other things, increases blood flow to the digestive organs and slows the heart rate. This is known as the “rest and digest” reflexes. When the sympathetic is active, it dilates the pupils, increases the blood sugar, increases the heart rate, and increases the respiration. In short, it triggers the “fight or flight” response, enabling us to take action.
The next time you notice yourself struggling in one of those unproductive days, try activating your sympathetic nervous system by using some of these:
- Sit up straight.
- Go for a brisk walk.
- Breath deeply and forcefully.
- Change to a more physical activity.
Many more suggestions on how tog et your sympathetic nervous system working for you if you read the full post.
One thing that military people will do to get ready for jumping out of a plane is to consciously flex and contract every muscle in their body starting at their toes. Not only does this help mitigate the flight response and change it to a fight response, but it also gets blood moving to all of the muscle groups. If you combine this process with 4–second breaths in expanding your diaphragm and 8– second breaths out to completely clear your diaphragm, you can get the sympathetic nervous system working while sitting at your desk.