At our school there is a lot of support for the "growth mindset". In summary, you praise the effort more than the results, believing anyone can do pretty much anything with enough effort (contrast with the "fixed mindset" where abilities are considered innate). Keeps children actively learning, and not resting on laurels or giving up because they think they aren't good enough. Seems to make sense - I remember reading about all the child geniuses that end up not amounting to much as adults, the theory being that they stopped putting effort in given they hadn't developed a connection between effort and outcome.

Just reading up on the "growth mindset" now, and it seems there is some recent criticism of the idea, although that stems from inability to replicate the research results, not that there is a more widely preferred alternative.