Ask yourself if you could be completely wrong about this concept: "To train any animal, you follow a simple process. You somehow indicate what you want it to do, and then when it does it, you give it a reward. Maybe in some cases you punish it if it doesn't do what it's supposed to do. Then you repeat until the animal is trained." 

I'm guessing you've never had complete responsibility for an animal, or a child. Following this concept to do so would be a dangerous experiment.

Positive and negative reinforcement are trivialized versions of pop Western psychology. Really not at all how animals or people work. If you want to begin to understand what truly motivates, I would highly recommend watching episodes of the Dog Whisperer - in particular, the shows where Cesar is correctly badly behaved dogs (most shows). You'll see dog owner after dog owner applying traditional concepts of behavior correction (training) who have unstable and even traumatized animals. What is it that Cesar understands that enables him to fix their behavior, sometimes almost instantaneously by simply giving a couple non-verbal clues? Like he says, he trains humans.

These will also help you start to understand: http://nymag.com/news/features/27840/ and http://www.ted.com/talks/dan_pink_on_motivation.html

The truth is much closer to "we are born to work".