This may be more theoretical than you are hoping for, nonetheless, I'd like to suggest Dan Pink's TED talk on The Surprising Science of Motivation http://www.ted.com/talks/dan_pink_on_motivation.html

Pink explains how financial incentives often have the opposite effect on motivation than we would want or expect. He suggests that the causes of true motivation boil down to autonomy, mastery and purpose. The video is worth the 20 minute investment.