Mindfulness vs. Mindlessness

I was at class on Tuesday, in the middle of a butt-kicker of a workout (coach was walking around making sure that our legs were burning because otherwise we were "doing it wrong"), when I realized that I wasn't sure how long our workout was that day. Coach had said that we had three minutes left for the set, but did that mean that that was all there was left total? All of a sudden, I had to know immediately. I started asking people, looking around for the white board (with the workout written on it), and trying to catch coach's eye so I could ask her. In retrospect, I'm not sure why I decided that I desperately needed to know, and I'm not sure that knowing would have changed anything anyway; it's not like I was going to stop trying (or that my legs were going to stop burning) if I knew that we had thirty minutes left instead of three. If anything, finding out that we had a ton more time left (thankfully, we didn't) would have just discouraged me.
One nice thing about having a coach and a well-written training plan is the ability to be mindless sometimes. That's not to say that I'm not mindful during the actual workout, or that I don't concentrate on the specific skill that I am drilling, but that there are some things (particularly the amount or duration) that will drive me crazy if I think too much about them. I've never, for example, admitted to myself while running a marathon that I had to run 26 miles. I pace myself for 26, sure, but if I start thinking at mile 5 that I have 21 more miles to go, I'll go crazy. So instead I concentrate on my foot strike or my breathing or think about the half marathon mark because that seems close enough (sometimes I also try to calculate my pace based on distance and time, which given my ability at math usually takes me a couple of miles).
In the same way, for all the intense concentration during some workouts, I think that part of training has to be mindless. If I start thinking about the duration of the workout, or the number of hours a week I am going to spend training, or the number of miles that I expect my body to cover on race day, I'll go crazy. Because running 26 miles is crazy. Even crazier is swimming 2.4, biking 112, and THEN running 26 miles.
So, I've resolved to stop thinking about it. I'm not even looking more than a day ahead in the schedule anymore because it just doesn't matter. Everyday I get my workout, and everyday I'll mindlessly follow it- mindfully.