The book 'Thinking: Fast & Slow' has a section on 'ego depletion' that may have some insight into your question. Basically when you think hard on a problem, make difficult choices, or work hard physically, you suffer from 'ego depletion' that makes further work even harder. This has a measurable impact on brain glucose levels. People given a glucose supplement don't suffer from the same drop-off in performance as those given a fake-sugar drink.

I hadn't thought about it in terms of Dweck's work on open-mindedness but it seems like accepting failures and persisting probably fall into the category of tasks that cause ego depletion. Very interesting.