How can I develop good writing habits?

Dear Literary Ladies,
With a full-time job and a thousand other things on my plate, my writing time is catch as catch can. Is it important to have regular writing times, so that writing becomes habitual?

I’m a full-time believer in writing habits…You may be able to do without them if you have genius but most of us only have talent and this is simply something that has to be assisted all the time by physical and mental habits or it dries up and blows away…Of course you have to make your habits in this conform to what you can do. I write only about two hours every day because that’s all the energy I have, but I don’t let anything interfere with those two hours, at the same time and the same place.

—Flannery O'Connor (1925-1964), from a letter