A developer, programmer, software engineer, call this category of work however you like, it uses the brain at such relentless limits, implicitly or explicitly depending on the problem a person it's currently working on, it takes an incredible amount of effort to relax your mind at the end of the day.
I remember working on a very difficult project for a customer and I would sleep for 4-5 hours per day until I deliver it, and by the end of the project I was so exhausted that I had to take a whole week to cool down my brain and relax my body.
It took me a whole month to fully recover!
I have worked as a construction worker with my father and I know how to grow my own fruits and veggies; I know the struggles with those things...but trust me, you cannot compare the two by any means!
Using your body exclusively it can be tiring indeed, but at the end of the day, you will have a nice shower, eat and rest well, and the next day you will be good to go; whereas with using your mind exclusively can be so dangerous in so many ways!
At least, that's my case.