Bad expectations, low blood sugar, too tired, it's the slow point of the day, the lesson has nothing new - so many reasons why one lesson can be boring, but man

Bad expectations, low blood sugar, too tired, it's the slow point of the day, the lesson has nothing new - so many reasons why one lesson can be boring, but many people (some of my class) don't break the habit. The only reason I find more than one lesson boring is that I didn't have time to rest between.