Chances are you won't believe this tip works until you try it out on someone whose feedback you trust.  Here's what to do.

Find a children's story with a good narrative and read a couple of sentences to your feedback friend. Her job is to pretend to be a five-year-old and tell you if the story sounds sufficently exciting. She's likely to tell you your voice needs to go up and down a bit more. (Just one caution: avoid the sing-song unnatural voice some parents use when reading stories to their children. Just more up and down to add excitement.)  Once you've got the 'yes, it's exciting' tick of approval, continue with a couple more sentences listening to the cadence (lift and drop) of your own voice.

Now switch to a few sentences from one of your serious work-related topics, still with the same cadence - as if it too were a children's story. Talk it over with your friend. Would that sound credible for an adult audience?

You're likely to be pleasantly surprised by the response.

So what's going on?  How can a children's story have anything to do with adult audiences?  When we feel nervous, our subconscious - doing it's job - kicks in to protect us. It compresses the natural up and down of our voices to make our words harder to take in. Get the significance? Please don't notice me. For many, the protective instinct is so strong they speak in sleep-inducing monotones.

The tip above reverses that problem. 

You don't even have to find a children's book. You probably already know the beginning of something starting with 'Once upon a time...'

Once upon a time, there were three little pigs. The time came for them to leave home and build their own houses. The first little pig built his house out of sticks. The second little pig built his house out of wood. And the third little pig built his house out of bricks... 

That should be plenty - go find a trusty source of feedback.  Wait... please lose any idea that speaking is only about conveying facts. Decades back, philosopher Marshall McLuhan said, "The medium is the message."  So right. You're the medium. You and your personality are a vital part of conveying any message. To children or adults.