I've long given one piece of advice that I think seldom gets voiced often by teachers or teacher trainers - at the end of a lesson or day with students, ask just one thing,

"Are you happy?"

And I get the students to say they are happy. Doesn't matter if they are happy or not - they reply positively.

You are probably wondering why that is so important? Well, please watch Daniel Kahneman's talk about happiness. He relates well how important it is how we end things, how important "ending" is to happiness (and also the story we make of it). The remembering self is so important to happiness, it governs so much of our time spent on earth. In learning theory we are finding out more and more how predisposed to "the negative" we are. But we can "hack our brains" through self - regulation and change. Just takes us to consciously retrain our brains. 

It's how you end your class that counts. It effects how the students will remember it. I won't bore you with my dumbed down explanations of why - listen to the Nobel Laureate and think of the implications for our own teaching and how we should end our classes with students.

If interested in happiness and teaching - see my own talk and resources here. Also, this guy's own thought.