I think we have very different definitions of unfulfilling. Doing something hard to stay alive is the definition of fulfilling in my book. What does fulfillment mean to you? The task in and of itself has to be rewarding? I'm purely judging by the outcome of the task and not how difficult the task itself is.

This is a definition of "fulfilling" that captures "subsistence farming".

Which many would consider fulfilling :) c.f. any farming commune.

c.f. impoverished rural Asia and Africa.

A lot of unfulfilling labor becomes "fulfilling" when you have the luxury of picking it up and putting it down whenever you'd like.