Does grit predict success? Yes — but only because it is conscientiousness under a new name.
Grit is a distinct trait, and the strongest predictor of who succeeds.
Credé, Tynan & Harms meta-analysed 88 samples (2017) and found grit correlates around r = .84 with conscientiousness — largely a trait psychology already had and already measured. The perseverance half does nearly all of the work; the passion half predicts little. Its value over plain conscientiousness for performance was small, and it predicted retention less strongly than the popular account claims.
Check it yourself: doi.org/10.1037/pspp0000102
Structure beats trait, and it is available to you today. If-then plans, commitment devices and a schedule you never renegotiate produce persistence without requiring you to be a persistent sort of person.
Every law on Useful Mind tells you how strong the evidence behind it is. The ones that failed are kept here rather than quietly deleted, because knowing which advice is wrong saves you as much as knowing which is right.
See the ones that held up