In my experience the warmer and more comfortable you are, the easier it is to sit still.
I like to dress as warm as I absolutely can and still shoot well and easily. Then once Ive shot a deer I usually strip off a few layers so I can deal with it easier.
Same thing with your actual stand being comfortable, my stand is a homemade ladder stand build from treated lumber, with only a 2x12 for a seat but its extrememly comfortable to me. It has armrests and I can lean back and practically fall asleep, makes it super easy to sit still. Not so easy to sit still with part of that tree in the small of your back, or your stand seat making your butt go numb,etc, etc...so try to make your stand as comfortable as you can to sit in, and as warm as you can. An investment Ive always thought about making is in a large blanket of some kind, preferably camo or dark colored. Would help you stay warm, especially your legs and feet.
I used to read also when I first started out, I found small pocket sized books to be best, fumbling with large pages of a magazine or something like that can really add a lot of unnecessary movement.
Like has already been mentioned, slow deliberate movements are much better than quick ones. I move my head deliberately slow (im thinking about moving it slow as Im moving it) and then I use my eyes to scan back and forth wherever my head is pointing....deer are good, but I really dont think they can detect eye movement at 100 yds away.
anymore I dont like the thought of keeping either my ears or eyes occupied with anything other than the woods around me. Sometimes it only takes seconds for a deer to appear, present a shot, and then disappear....if youre using these seconds to dig into your favorite Twilight novel...youll go home empty handed.
With the ears, if you can hear a deer walking it usually very close by and you need to be very cautious. They make other sounds too, which can be beneficial to hear, grunting, fighting, snorting alarms, etc....all of this you miss out on by having your Ipod cranked up. Not too mention the other sounds you miss out on.
As for smoking I had a late uncle that constantly had a cigarette in his mouth, hunted on the ground, and I dont think ever had an unsuccessful hunt.
In recap, for me personally the biggest elements of being able to sit still are being warm and comfortable, if either of those is unfulfilled I really have issues sitting still.