I watched this TED Talk by Shawn Achor a few years ago, and it still has the punch it had back then.
It is a great example of stage presence, use of comedy and story telling. All are amazing. You can see when the camera pans to the audience how every single one of them are super engaged. On top of all that the actual lesson itself is amazing.
This was a great little Saturday morning watch, I hope you enjoy: http://www.ted.com/talks/shawn_achor_the_happy_secret_to_better_work.html