Ask HN: How to be more productive during waits?

During my regular work day I find myself often waiting for things to compile, build, then deploy etc.

When that happens I tend to have a habit of either reading the news, going to social media (FB, instagram) or watching youtube.

Some days, if you add that time up across entire day it ends up being 1-2 hours. That's extra 2 hours a day, spread out in 5-10 minute chunks, that can be used for something that doesn't degrade my brain.

What suggestions do you have to fill those gaps with more productive tasks?