The very first thing I do when I enter my classroom in the morning isn't turning on the computer, or opening my lesson plan book (well, that's already open usually, from where I left off the day before), or check voice messages.
The very first thing I do is just sit at my desk and gaze off into space for a few minutes.
I like to savor the quiet of the room, and how clean it is, and how calm it is. And I think about the productivity that's going to happen in that room throughout the day. I imagine the path I take when walking around, monitoring students. I move the furniture around in my head, wondering if I an rearrange the space for a different effect. I think about moving students - who shouldn't sit next to whom, et al.
I think I like those first few minutes the most out of my day. It's just nice to be the only one in the classroom sometimes. It's nice to gather my thoughts and gear up for the day. It's my own time - with no interruptions, since I arrive so early that the only people on campus are the custodial staff. It's a time of absolute potential, when I haven't yet failed at teaching a student that day. When I haven't made a mistake, or gotten pissed off by a kid, or parent, or both. When I haven't been drained of all energy yet.
So I just sit, sometimes thinking, sometimes just being. It is a really refreshing moment.