I usually felt guilty whenever i spend a couple of hours doing nothing. Usually those breaks come in because either a) i know i have a lot of time to complete my tasks 2) i don't have much work to do.

Then i started going to office after years of WFH and noticed the amount of time we spend on coffee and lunch and still being called productive because of those same two 2 points .

So i implemented a plan , when on WFH, i started playing chess during those long breaks. Believe it or not, the breaks were reduced gradually because either i win a lot and then i move over or i lose a lot and then i move over. goes without saying, your mileage may vary

Slowly after making it a habit, i was greatly able to reduce my non productive time to somewhat productive. like reading something about the tech or learning ..

Now being productive can be a subjective thing. you might read a lot about tech that has nothing to do with your job , so you are not productive for the company you work for , but still being productive to oneself.