Back when I was about 5 years old, there was a class we had to endure on things like underlining the vowels in sentences the teacher wrote on a board for us to copy and underline. Or learning how to address an envelope.
It involved a lot of waiting, because it was super-trivial and involved a lot of doing nothing. It was there that I remember realizing that I could use such periods of time, or any periods that would otherwise be boring, by using my imagination in elaborate considerations about whatever I wanted. That and one other lesson about feeling bored from my mom about the same time, and I’ve rarely been bored since. I do find it helpful sometimes to have something to write with/on. And with portable Internet devices, no one these days should have much excuse, unless they’ve not realized how they can use their imaginations yet.
It only doesn’t work when something makes it too difficult, such as illness, great fatigue, or other distractions.