So, no, I can't take the car down to the DMV to get the emissions tested at 11. I can't run a bunch of little errands because it's not my day off. I need all 8 of these hours in an unbroken stretch, and if I do it right I won't even find time to stop for lunch. It's tough to communicate that to your partner, especially when she comes home at six to find you in your bathrobe playing Fantastic Contraption (, relaxing after a long productive day, but it probably doesn't look like it.)
Like most things, a lot of it comes down to self-discipline. I tend to start the day at 8am with a cup of coffee and a walk up the stairs to the office. As the author says, there's nothing wrong with a little bit of schedule, so long as you remember to take advantage of the upside of running your own business. If the sun is shining at noon, chances are you'll find me out in the hills with a pair of rock boots and a bouldering mat.