What hurts after your class?

With the coming of the new year, many of us (myself included) have made a “recommitment” to living a healthier lifestyle.  This includes physical exercise, diet adjustments, etc.  I have recently begun my own “recommitment”, and find one common denominator among all aspects of this adjustment.

It hurts.

When I change my diet, my stomach hurts as it gets used to being a little less full.  When I exercise, my muscles hurt from exertion and my lungs hurt from heavier breathing.

So, as I was laying down last night trying to recover from my workout, I thought:

If my class is supposed to be an exercise in learning, what “pain” should I feel as the teacher? 

What “pain” should my students feel during and after a lesson?

Should there be any “pain” at all?

If not, then what can we do as educators to provide any necessary “intellectual anesthetics?”

As a doctor (albeit a doctor of philosophy, not medicine), I am interested in an answer to these questions.

Oh, if you have any tips on how to effectively “recommit” to a healthier lifestyle, that would be great too!