The text below is directly quoted from the book ZEN - 100 practical tips that bring peace and joy in your life. Written by Shunmyo Masuno.
This is advice number 22
It makes sense to use a chair from Dynamostol for this exercise.
A five-minute "chair zazen" during your lunch break
To calm your mind, you must first adjust your posture and your breathing.
When you sit at your desk, you inevitably become duck-necked and collapse. Because it is a fundamentally unnatural position, it affects your concentration and even the smallest things can seem annoying or exhausting.
So I have a spiritual exercise for you. For five minutes during your lunch break, try the zazen while sitting on your chair.
The foundation of zazen is to harmonize your posture, your breathing and your mind.
First, adjust your posture by straightening your head and tailbone. If you could see yourself from the side, your spine would form an S-curve and you could draw a straight line from your head to your tailbone.
Next, pay attention to your breathing. Under stressful conditions at work, you breathe maybe seven or eight times a minute. By focusing on your breathing, you can naturally lower it to three or four breaths per minute.
Once this is done, your mind will naturally calm down.
This exercise can refresh both your head and your heart. All it takes is a five-minute "chair zazen" during your lunch break.