For me, it depends on the time of the year.
I own a small publishing company, and I teach a writing and disaster analysis course at my local university. For about 4-5 months of the year, around half my time belongs to the university. The other half is used for building my business. When I'm not teaching, I'm working on building my business and any professional commissions.
So, right now, most of my writing is close to full-time hours (in fact, I'm racing to get The Odyssey of Daiki Yamato finished before my main course prep starts next month). That said, it also all gets folded into my business in some fashion (so, I wrote Re:Apotheosis full time, but I then typeset it and prepared it for publication - the same will happen with The Odyssey of Daiki Yamato).
It's a fulfilling life, but also one where one doesn't make a huge amount of money. So, when it comes to doing what I do, your mileage may vary.