It really depends on the person. Asimov was amazingly prolific as a writer, and just never stopped. He found something that he loved, that he was good at, and that would pay the bills - and he just did it every day. In fact, he wouldn't even dwell on past things he'd written.. because that time was lost that he could be writing new things (had a policy of "twice through the typewriter" and then he'd never look at it again).
Some people just have that mentality - their work is their hobby, and their work is what makes them most happy - and it seems as though Ash does.
Edit: There's a story where Asimov's wife made him go on vacation to Cape Ann, MA. He ended up meeting with a college group that was trying to write a parody of Kiss Me Kate... and spent the entire week in with them writing lyrics, never going outside. He never even took time to go see the show they had written together before he left. The joy was in the work itself.
