Steve blogged recently about how he tries to adhere to a schedule of writing daily, and of focusing on a given project per day. Working on one thing for a couple of hours, then switching away for another thing for a while, then another, etc. tends to have a debilitating effect on him. Context switching, he found, ran contrary to the deep immersion that creative work demands. I think this is true of most anything, especially writing; "getting into the zone" is antithetical to the relentless chopping-up of the day into pomodoro-sized bites.
Some readers know I program as well as write. I wrote the software that runs this blog, and I have some other projects stewing away in the background — a toy programming language, a toy web framework. It takes at least an hour's commitment of time, sometimes two, to get anything worthwhile done with those projects. A lot of that is just establishing within one's self the permission to sink deeply into the work for a solid block of time, to know that you don't have to drag yourself out of it except perhaps to quit for the day, eat, sleep, read recreationally, ride around the neighborhood, pet cats, etc.
The hardest thing to deal with is the feeling of "I should be doing X instead". I should be putting in laundry; I should be yanking weeds out from between the cracks in the sidewalk; I should be calling my cousin whom I haven't spoken to in years, etc. For a long time I had to fight with having a low threshold for this kind of distraction, to give myself permission to do something for hours on end and not feel like the world was going to end, either in whole or in part, if I did. The only way I was able to fight it was, in the end, to just do things and let chips fall where they may, and teach myself from the gut level on up that what actually happens to us anyway is nothing like what we imagine it's going to be like, especially if it's bad.
It's hard to just do things, because our ideas about them always get in the way. It's hard to just write, because we do have to think about what we're doing, and once that door is opened all sorts of vermin rush in from the garage outside. But there's a difference between thinking about the work itself, and thinking about working.
Last note. I suspect people expected a rant about digital distractions and social media, about how our attention spans have been destroyed, etc. It's partly true, but I think it's something that has to be fought on two fronts, external and internal. By all means, work to make these things less rapacious and disruptive. (A social network with no advertising at all, subsidized entirely by goodwill or user donations, a la the Internet Archive, sounds like a good start.) But do also begin from the assumption that you have the first right of refusal, that you're not entirely helpless and that this stuff begins with your own willingness to turn it off. Just don't assume other people are wimps or turncoats because they don't start there. Give them as many excuses as you can, though, to join you.