Joli Jensen, a University of Tulsa professor who leads writing workshops for academics, has some sound practical advice about scheduling time for writing:

One of the most widespread myths in academic writing is that you can, and should, try to “clear the decks”—that is, finish all of your other obligations before you can focus on your scholarship….

The reality is: Things never clear up. They don’t even reliably settle down. Your in box is always full. The decks are always crowded. There is always more going on than you want or expect. Nonetheless, you can find ways to put your writing first, and make sure that it gets done. Otherwise, everything but your writing will get done.

It’s not just academic writing that suffers from this delusion; people in other walks of life share it. But unless you’re single, an orphan, have no pets or plants, and all your belongings fit in a rucksack, when you start writing there are always going to be other things demanding your time and attention. Always. So the challenge is not to get rid of all of them, but to be ruthless about setting aside time in your day to write (or paint or compose etc.) and stick with it.