I've never thought myself much of a romantic, and I don't think anyone who knows me well would either, but then how else would you explain my fervent teenage belief in writer's block? My first full-time job, writing for high profile, very high traffic site, quickly disabused me of this notion, as we were all expected to produce twelve pieces minimum each every single day. It was excruciating, and I was pretty unhappy at the time, but it cured me of ever thinking I couldn't sit down on any given day and chip away at something. 
Anyway, as a lifelong knowledge worker whose friends are mostly lifelong knowledge workers, I've always found Henry Miller's commandments (from Henry Miller on Writing to be helpful. (I'm still not as productive as I'm capable of day-to-day, nor as prolific as I should be, but I do get better year after year at working with pleasure!)
- Work on one thing at a time until finished.
- Start no more new books, add no more new material to "Black Spring."
- Don't be nervous. Work calmly, joyously, recklessly on whatever is in hand.
- Work according to Program and not according to mood. Stop at the appointed time!
- When you can't create you can work.
- Cement a little every day, rather than add new fertilizers.
- Keep human! See people, go places, drink if you feel like it.
- Don't be a draught-horse! Work with pleasure only.
- Discard the Program when you feel like it—but go back to it the next day. Concentrate. Narrow down. Exclude.
- Forget the books you want to write. Think only of the book you are writing.
- Write first and always. Painting, music, friends, cinema, all these come afterwards.
Bonus! People share Miller's commandments all the time, but the next section is just as important to work/life balance, especially for freelancers—and most especially for introvert work-at-home freelancers such as myself, for whom making the time to socialize can require a lot of effort.
If groggy, type notes and allocate, as stimulus.
If in fine fettle, write.
Work on section in hand, following plan of section scrupulously. No intrusions, no diversions. Write to finish one section at a time, for good and all.
See friends. Read in cafés.
Explore unfamiliar sections—on foot if wet, on bicycle, if dry.
Write, if in mood, but only Minor program.
Paint if empty or tired.
Make Notes. Make Charts, Plans. Make corrections of MS.
Note: Allow sufficient time during daylight to make an occasional visit to museums or an occasional sketch or an occasional bike ride. Sketch in cafés and trains and streets. Cut the movies! Library for references once a week.
The only improvement I'd make to Miller's daily program is to get a dog—if you live in a city, having a dog both makes it easy to get regular exercise and be social, because taking a dog for a walk instantly means you'll meet a lot of people in your neighborhood. 
 Having said that, while writer's block doesn't exist, the zone does. Working with people who never get there, and thus have no respect for it, make getting shit done hard by doing stupid things like organizing meetings in the middle of the day. Most meetings are pointless.
 The last time my mom came to visit me here in New York, she wondered why people kept waving at me while we walked around my micro neighborhood on the Lower East Side: "Are you the mayor or something?" I explained that everyone knew me because they were all Friends of Jarvis.