A new study from the University of Leicester proposes that the happiness of freelance workers -- contractors, copy editors, coaches, designers and, we assume, writers -- depends on a few key factors, as does their anxiety and depression. 

"Conflicting demands that constrain and hinder people from smoothly fulfilling their tasks and achieving their potential adversely affect their work-life balance and well-being," Science Daily explains. If the freelancers have control over their work and the work itself is varied, they will be happier and more enthusiastic. (Just like everyone else.)

However, this "enthusiasm-based interference" is more relevant for freelancers whose frequency and payment per assignment tends to fluctuate. People who get paid a standard rate per standard project are just happier to get more work.

Researchers also note: "Demands thus generate what has long been called stress-based work-family/non-work interference but hours generate a largely unrecognised phenomenon, enthusiasm-based work-family/non-work interference... The calmness associated with long hours has, though, the opposite effect -- it decreases work-family/non-work interference."