The problem with making an extrinsic reward the only destination that matters is that some people will choose the quickest route there, even if it means taking the low road. Daniel Pink
(p 51 Drive the Surprising Truth about What Motivates Us. 2009.)
Goldilocks tasks — challenges that are not too hot and not too cold, neither overly difficult nor overly simple.
(p 118 Drive the Surprising Truth about What Motivates Us. 2009.))