I think the idea of "do what you love and the money will follow" is naive at best. I prefer the thought that all honest work is honorable no matter how "lowly" the job might be. I did a stint as a janitor for a while - hardly anyone's dream job, but I gave it my best shot and felt satisfaction when I left my spanking clean building at 2:00am each morning.
That said, my ex-husband always loved the out-of-doors and fly fishing in particular. He wrote a book about his experiences in the Forest Service which was a total flop. He did eventually become a successful fly fishing author, getting published in national outdoors magazines. He now makes a good living writing, lecturing, and guiding fisherpersons. So, it can be done. Pragmatically, the fact that he was married to me and I made a steady income, including health insurance was extremely helpful to him in the early years. (and no, I wasn't a janitor, I was an educator
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