"It’s oddly difficult to do nothing"

This isn't always true. It's likely true only when there is no pressure. However, when there is pressure, one can "do nothing" for long periods. If you haven't experienced that, you've lived a blessed life, and you have more to learn.

I think you're equating doing nothing with doing nothing productive. You're usually still ruminating or trying to distract yourself from the source of the pressure.

What is an example? I can only think of a root canal procedure.