Zen Habits has a little post on something I've been practicing ever since I left my last corporate job and started my own firm: Leave the clock behind.
Now, before I get started, let me state that there are times for clocks: Need to be on-time to a client meeting, or (even more importantly) keep a meeting focused and on-track by limiting its duration? Have a court date? Other professional obligation? In those cases, yes, yes, YES, clocks are your friend. They keep us in sync with the rest of the world, keeping the trains running on time, metaphorically.
But this isn't about those cases. It's about the other 90 percent of your life.
In the rest of your life, ideally you don't need a clock. Your body tells you when you are sleepy, when you are ready to awake, when you're hungry, and so on. And your finely-honed sense of professional duty and personal passion for what you do tells you when to get to work (right? right?). So what's the clock for?
Now, yes, yes, YES I know: I am not chained to a cubicle, with a nefarious middle manager lording their supposed superiority over me. I am fortunate to run my own spread, and work with people who are responsible enough not to need much in the way of a clock, either. I'll give you that. But I've got to tell you, there's a lot to be said for waking up when you are no longer sleepy; eating when you are hungry; working when you need money (which, in the face of $4 a gallon gas, is pretty much every minute I'm awake).
My point is that if you live without a clock telling you when to do things, you are letting something else tell you when to do them. Like your body, or your mind, for instance. And I think that's a good thing.
Creatively-speaking, what does this do for you? Or for your clients? Well, if you're not clockwatching, then your are more likely to be actively engaged in your work. You are more likely to be thinking, and not just doing (which is to say: you will be doing your doing better, since you'll be paying more attention to it).
And as your ruler-toting nun teacher (or in my case, sharp-tongued and eagle-eyed philosophy teacher) would say, "if you're paying attention, you're learning." And isn't half, or more than half, of what a designer, marketer, copywriter, or artist does simply listening?
I posted on this topic a couple of years ago, relating that back in the 1600s, the village blacksmith didn't sit at his forge for eight hours, then go home. He worked when there was work that needed doing, or when he was feeling particularly inspired--whether that was at noon or at ten at night. The rest of the time he was, you know, being human. which is to say: having a life.