Use a quote that will stay with your audience members long after they leave the room.
I saw a fantastic presentation on what it takes to motivate a staff. The manager had provided a list of tips and techniques that worked for her, but I most strongly remember how she ended the presentation.
She listed each of her approaches with this simple quote in white letters on a black background emblazoned on the screen behind her:
"The simple act of paying positive attention to people has a
great deal to do with productivity."--Tom Peters
Her entire presentation had been about positive reinforcement and while I can't recall all of her tips, I will always remember the quote.