Same. But my brain is consistently thinking about stuff. I wonder if it's still rest?
If I understand the article correct then rest is not about “not thinking”. Rest can also be about engagement (for example sports or a making music). Just using different parts of your brain which are usually not directly used for work.
If it never stops thinking try meditation practice, it will help after a couple times already (for me at least).
Also sometimes it can be good to “reset” the brain by going into the wilderness or a retreat or have a day nap.