One thing that has surprised me as we've visited so many churches after returning to the US is how long sermons (messages) have become -- none under 35 minutes -- at least one over 50. Frankly, I don't get it. With the way media has developed I thought things would be going the other direction.
At exceptional communicator might be able to hold someone's attention for 40-45 minutes utilizing a conversational oratory style. But I can only name two or three such people (and I doubt any of them read my blog). Most really good communicators can't hold people's attention longer than 20 minutes. There are too many who should stop at about 5 minutes.
I try to speak less than 20 minutes when I preach (and even that is pushing it for me and my audience). That doesn't mean I'm always successful at condensing things to that amount of time -- but that's my goal. My ideal sermon is when I can sift through the text and condense it all down to 12 or 15 minutes. But that's hard -- really hard -- and it requires more preparation time. (Longer sermons often mean that the preacher hasn't prepped enough to get focused.)
Here are some things that might help:
1. Choose a single narrative or metaphor to carry your message all the way through the message.
2. Condense your sermon down to a single point before you add stories or sub-points. When you're done developing the flow, check the sub-points and stores in relation to the main point -- and eliminate the half that don't fit.
3. If you feel that you have to go longer than 15 minutes use a more interactive style. Ask questions, catch people a little off guard, engage in actual conversation with the "audience," include an interview...
4. Use a video clip or prop -- a memorable object. But don't use the same kind of media in every sermon. Don't use a video clip each week or a song every week. If your object is too predictable it isn't as engaging.
5. Break things down into smaller bite size pieces. If your style involves textual exposition don't feel like you have to cover a whole chapter. Sometimes working with two or three verses is more effective.
6. Focus more on the public reading of scripture and have your message flow from that -- rather than using scripture to make your points. If there are biblical passages which back-up what you're saying it isn't necessary to read every one of them.
7. Bring the children's sermon back into the service. It gives you a chance to make your point in a completely different way -- often prepping the adults to later hear what you're saying on a more developed level. (And it helps the kids feel like they're a part of what's going on.)
8. Pulpit transparency is a good thing. But some preachers are spending too much time talking about themselves -- more time talking about the challenges in their lives than the gospel itself.
9. As you develop your message tie it into the big biblical picture. That will keep you from spending an inordinate amount of time developing small (fascinating to you) details in the text. It will also keep you balanced with appropriate levels of law and gospel.
10. Create a conversational style manuscript of your message. I know that some are being taught to spend less time preparing the sermon and more time preparing themselves -- and then just to let it flow more naturally as they are led on Sunday morning. That might work okay for the occasional preacher but you'll communicate more clearly if you work through what you're going to say ahead of time. The Holy Spirit is more likely to tell you what to say as you prepare than when you're standing there in front of people processing ideas on the fly. And you'll be more focused!