Don't overwork yourself, you won't get anything done if you aren't motivated. It might not feel FUN all the time - because there's actual work involved - but if you're forcing yourself to work more just to meet some arbitrary quota you're planning your work wrong. If you're just doing indie games as a hobby, then work when you feel like it. If you're making commercial games, make sure to work on them enough that you actually get games done at a reasonable rate. But make sure you take breaks, because burning yourself out will just lower your productivity in the long run.