Do Some Easy Work
In order to calm down after a long and nerve-wracking meeting, switch to an easy task. Maybe do some administration, read some notes, clean up your desk. The idea is to keep working and stay productive, but with much less strain.
By doing so you will lower your activation level (energy expenditure), and give your rational brain a chance to recover, as you are not forcing yourself to think intensely.
Furthermore, doing easy work can add to your feeling of being in control, which can be a welcome change in a situation where you felt the exact opposite.
Note: It is good to realize that performing easy work only goes that far and only lasts that long when it comes to slowing yourself down. So don’t forget to take a real break later on.
