A good sermon in the pulpit will reflect hours of work in the study. Hours of prayerful reading, careful thinking and sometimes tearful wrestling through the process. But no rule says preparation has to happen at the desk. In fact, the desk can be a place of distraction!
Personally I tend to work either at home at my desk, or at a friend’s house (quieter). However, there are times when I find I need to prepare somewhere else. Not because I have to, but because it helps. I sometimes think and preach through a sermon while driving (sorry for the carbon footprint!), or on a walk, or pacing around in my living room. One time I had to answer questions from the police about what I was doing at such and such a time (“Uh, I was preaching a sermon while staring out of the window, officer!”) – I happened to fail to see anything suspicious as a crime took place down the street, but my bizarre excuse precluded further questioning!
Anyway, where do you find preparation works best for you? Driving, walking, pacing, sitting in a Starbucks to see and sense the reality of people? There are no rules here, but I am interested!
Biblical Preaching 
I have often called my office the Black Hole of Inspiration. There have been times that I’ve spent eight hours in the Black Hole not getting it right, only to go vacuum the house and have it all fall into place for me before I finish the carpet. Sermon prep “in” a vacuum isn’t nearly as good as prep “on” a vacuum!
Seriously, if you can’t figure how to organize your sermon, I highly recommend doing the floors. It might also work while cleaning the office, but I haven’t tried that yet.
I prepare at a coffee shop. As long as I am alone, I can have a lot going on around me and still get what I need. I can study, pray, and yet see culture as a way to apply. I ask, “What would she think?” Or, “What would I need to say so that guy would get it.”
My wife and I are both ordained pastors serving churches. So, we tend to talk out the implications of texts just about anytime: while driving kids to school or attending denominational meetings or going to the movies. For us, and this may seem a bit odd, the best time to talk is before going to bed at night. Both of us strongly believe that the gracious time of letting go of the day allows our subconscious and God’s Spirit to work together. It doesn’t happen very often for me, but it’s not unusual for Amy to awaken with a sermon nearly fully formed in her mind. It’s eerie, and I’m a bit jealous! I have to wrestle more!
I do much sermon preparation while driving. I find it easier to think through a text while on the road than in the office.
The best insights usually come to me in bed around 4-5 a.m. I haven’t found that sleeping more and studying less actually helps, but once I’ve sweated through the study, I apparently go over the material in my sleep and the thoughts come together when I actually relax and quit fretting.
I prepare in all of those places, public and private. I’ve found that, if I get familiar with the text early on, preparation is an ongoing process. As I try to learn as much as I can about the text, I may get inspired anywhere and at any moment.
If I’m struggling with passage, I’ve found it helpful to get away from any place too comfortable of too accessible. When I’m working hard to bring the message together, I need to concentrate without interruption and without the distractions of my home or the office. A booth at a restaurant (preferably on that offers free refills…Panera anyone?) or a quiet coffee shop work best for these times
I find that I need the structure of the study for exegesis. I sit at my desk surrounded by my books and work through the text until I understand it.
For the sermon preparation, however, I find that the connections for the sermon usually happen while I’m out and about, eating, visiting, talking, taking my walk, etc.