Some of the psychology explaining how people work - which also helps business people see the connection between how the mechanics of people matches Lean practices and why it engages employees.
David Rock
[youtube https://www.youtube.com/watch?v=XeJSXfXep4M&w=425&h=349]
another link if that doesn’t work:
https://www.youtube.com/watch?v=XeJSXfXep4M