Personaly, at first, when I first started smoking, I would forget full blocks of time. Any time I would zone out, that section of time would be void (concerning the events around me). Even internal events would be screwy. I would try to set my alarm clock and it would take me way, way, longer than usual just because I would do stuff like:
"OK..."
"Um, OK..."
"So, all I gotta do is, um..."
"So, first, I press this button, and... um..."
"Uh..."
"What am I doing? ... Thats right, ok, um..."
"This button and I click this one until..."
"Until..."
"Uh, what?"
"Hold on, what time do I need to get up at?"
...
But that never happens anymore. I found out that I was usually just fighting myself most of the time. After I got over that and allowed myself to just flow with the action, everything happened smoothly, even if I didn't comprehend what I was doing. All I have to do is state my intent, my direction, and set my body in motion. Then my body does the rest, right in front of my astonished eyes. Its like picking up an object with a numb hand: you can't feel the object, and you can see that its in your hand, but your hand isn't giving any feed-back on the matter. You give your hand the intent and it follows faithfully even though it doesn't know what its doing.
Also on the subject, I've played guitar enough for me to be able to improv somewhat. So one day I got blazed out of my mind and picked up the ol' six-string. I started to play and it was the most amazing thing: the notes sounded great, they all fit together and stuff, but I had no clue what I was doing on the guitar. I just sat there and watched my fingers dance around on the fret board, producing this great music, all without my awareness having to intrude. But when I tried to concentrait on what I was doing, everything went downhill: I fumbled around, I didn't know what to play next, etc.
My point is, I guess, is to just state your intent, set your body into motion and just trust that the outcome will be what you wanted. Thats all I do anyways

And if that doesn't work, then hey, the outcome couldn't have been much different than if you actually tried to focus on what you needed to do!
l8r
-Zoad