So how do I get things done? The first, and most important factor-I don't consider creative writing to be work.
Sure, it takes effort, and I have to make sure what I'm writing isn't complete garbage (although that's what editing is for, too). But sitting down and banging out 500-1000 words of one of the stories I'm working on per day? Not stressful. It's rarely, if ever, something I have to force myself do. Sure, there are plenty of times I have had to put one story aside and work on a different story until inspiration struck, but something always gets worked on at least once a day. Writing is a reward by itself.
I also don't have too many other activities. Some people may consider this is a negative, but I've always been an introvert. I like hanging out with people when I have plenty of time for it-on weekends or vacations, for example. But after work? I don't have the energy to hang out with people, or stay out late drinking. I much prefer to sit in my apartment and work or do solo activities. Even before I got heavily into writing, I would be quite content to read, play videogames, or watch anime. I don't require a ton of social interaction to be happy.
That said, there are occasions where I can't get any writing done. I don't do well without sleep. If I have to get up early too many days in a row for work, my writing suffers. When I get sick and have to go into the lab and work through it, my writing suffers. When I get migraines (which happens every so often) my writing suffers. For whatever reason, despite writing not being work, I have an easier time going to work and doing busywork while feeling ill or exhausted than I do getting writing done when I'm not at my best. Maybe being creative just takes more energy.
I often wonder what my productivity would be like if I did write full time. While it is my dream, there's always the fear that if it happened, I would lose the structure I've built up by having a 9-5 job. At worst, my average productivity would stay the same, and I would just do a lot more goofing off. So maybe having the job isn't such a bad thing.
Besides, if all goes well, I'll be a PhD!