By the way, I'm not as interested in motivation in the sense of getting kids to want to run. I'm more interested in two things:
1. Getting the kid who already really wants to run to be more fired up about his/her training (seems to be different for guys/girls), and maybe want to do the little things better
2. In response to a particularly good/bad workout or race, to get the kid to take that success/failure and use it as motivation or to (re)focus toward the goal
Is it just a matter of figuring out what the kid is hoping to be sold and doing your best to start selling that? It certainly doesn't seem to me that all good athletes feed of the same, or even similar, drives.