My wife is about to embark on a Theology degree and one of the books to read in advance is How To Write a Theology Essay by Micheal P Jensen. I'm reading it as well so that we can discuss what it covers and came across this:
Thinking is actually hard work.
Now it doesn't look like it is, because you do a lot of it sitting down, and you don't sweat much doing it. You don't get callouses anywhere, and you don't put your back out for the most part.
But it is hard. Done properly, thinking is exhausting. That's why we watch TV – because it is like we are having someone else do our thinking for us.