[johnsmith4739]

I'll give you an even better one: locus of control

People with internal locus of control are 5x more likely to use failures as stepping sones toward improvement. I know because we did the research. We use this, among other behavioural traits, to recruit talent.

[sn41]

Locus of control is indeed mentioned in the paper as one of the factors that might explain the development of grit.