Typically whenever I teach lessons, I will wander around the room and not laugh or joke or anything just continue teaching until the bell. Last week I made my first noticeable improvement in my enthusiasm.
In my Small Gasoline Engines class, We had just finished going over the different tools we use and I was starting a lesson on the four strokes of an engine. It started off a little bit slow with the students not really wanting to answer my questions.
As I said, Enthusiasm has never been my strongest teaching characteristic, but ever since then I have noticed myself acting more like this in other classes also (most notably my 1st period small animal science class, they are always still asleep.)
Every day that I teach I notice myself improving little by little.