If I'm honest, I can summarise the reason in one word: internet.
I have to admit that I'm as susceptible as the next person. Facebook has these flashing notifications that come with booping noises, and they distract me from my work. Every time I get a new email, Thunderbird shows it to me in the lower right corner of my screen. These two things - email and Facebook - have successfully derailed a number of my editing and writing sessions. I'm sure both these programs are conspiring to make fools of me.
So every now and then, I fire up this old laptop - which is affectionately called "The Brick" because it's about as heavy as one. Then I work for an hour and a half. Later, I resurface after a successful editing session.
No internet! My strategy worked like a charm.
Everything today seems to be so immediate. Twitter notifications, Facebook notifications, and the like all show up on the home screen of your phone. You're busy writing, and someone decides to chat with you on Facebook. Things start flashing and booping.
Goodbye work time. Hello fun - I think ...
I say this because Facebook is possibly one of the most boring inventions ever. I literally just scroll through the feed several times a day. I don't really do anything on Facebook. It's just there. And there are all these annoying profile pics that get changed every day and all these people bragging about their accomplishments or trying to elicit sympathy for some cryptic situation they haven't outlined. Looking at Facebook is like stopping work just to spy on your neighbours for a while. To quote Monty Python: "It's dull, dull, dull, and desperately dull."
But unfortunately, I have to admit, Facebook is distracting. This is why I fasted from internet for a while this afternoon. Any time you want to get something done, I advise you to do the same. Writers can't live without the internet - this is true. They need it for research and advertising and all that stuff. But we can't always work with it.