We are young and do'nt call us the old~~

when we have an English oral-praticing class, my teacher, an old professor from Australia, said to us that we looked so old than we really were.
We asked why, he said that we were lack in passion.During the class, almost no one asked a question, and always made a distressed expression, smiled a little, we were too pessimistic.
Yes, partly I agreed with him, some students were not so activity, they received so much stress from the society.
But not everyone, and as I know, I"m not.
And people are different from each other, we just have a different way to express ourselves.
I hope you can tell me how you classmates express themselves? Or what do you do in the class? I'm so wonder to know.
Please tell me.