Be Willing to Feel Less Productive

Correct. Taking a break or having a rest is for better productivity. I've experienced it myself and seeing colleagues who spent many hours trying to be productive but it is not helpful. At the same time,personal mental and physical health becoming worst, which eventually causing even lower productivity, a bigger mess.

A classic example is sleeping.

I've met many people who were trained to feel guilty for sleeping, because it is "unproductive".

In reality, while you sleep, your cells get busy revitalizing your body, preparing for productivity.