The idealized life of a writer often seems to involve working no more than 3 hours a day (from your house). I blame television and the movies, which always show writers simply typing up their perfect, well-formed thoughts, usually at the end of their last paragraph.
The reality, of course, is that to be a full-time writer, it needs to be treated like a full-time job. Today, I spent over 5 hours on a call with a friend to plan/coordinate/map out a potential collaboration effort. There is still more planning to do, but we made a lot of headway.
Of course, it is always easier said than done. If you already have a job that takes up 8 hours, it is hard to dedicate another 8 on writing. But do what you can. Even if you just write as a hobby, try finding a free day and actually treating it like a writing workday. Schedule a block of 8 hours and get work done. At least try to get work done. If you find yourself drawing blanks, try all the writing techniques you know to get the creative juices flowing. Otherwise, it will end up being a very long 8 hours.
I admit that I do not often make myself follow this advice. However, I do periodically find myself having spent a day doing writing or other creative work and realizing how great it makes me feel. If you haven't tried it out, at least give it a shot.