I can relate to this. It might not have been the same level of intensity physically but I worked as wait staff for a couple years in my mid-twenties and despite my exhaustion at the end of shifts I always felt good. I have never once felt the same about my full-time programming job. On the contrary I have gone through what I can only describe as deep burnout twice in my 15 year career and those burnouts lasted agonizing months of time. It was brutal.

For me I think it is the level of perfection that is required to actually have development proceed smoothly. It is extreme particularly when coupled with peers who frequently break things or put together solutions that are overly complex or bug riddled.

Don't get me wrong, I am not a perfect programmer by any stretch of the imagination but it is my desire to reach perfection that causes severe emotional drain I think.