A switch flipped in my head at the beginning of my lectures last spring. At that point I had lectured something like 5 full university courses and maybe something like 50 research seminars. I was an experienced speaker.
But I was fast.
You'llnoticethisifyouaskmeaboutsomethingresearchrelatedthatI'llstarttogetexcitedandtalkfaster. In my personal life, I'm much more laid back, but at work, I talk fast. It is what it is, I suppose, but it's not the best attribute for an effective lecturer.
And then last term something happened. I walked into class and started speaking twice as slow as I ordinarily did. I liked it. I felt that I still had the amount of energy that I should have, just... slower. I don't know what I did, so I couldn't tell you how to do it if you wanted to, but now I can turn on the slow mode whenever I want.
Actually, I just thought of a theory about what I might have been doing. In every sentence when you're speaking, there are few key words that you emphasize. When you get to those---and you should try to anticipate those words before you say them---exaggerate your emphasis and focus on slowing those words down. Then the other words in the sentence, and the length of your pauses, will follow. That might be how I learned to switch, maybe. Let me know if you try this and it works for you.
Another nice thing about speaking slower is that it gives me more time to plan my sentences. This reduces the number of times that I get halfway through the sentence, think of a better way to say the sentence, and start the whole thing over from the beginning---a bad habit of mine.
It's nice to know that you always have more to learn. This change sure messed up my lecture plans for that term---everything took longer than I expected---but overall a positive change, I think.