Mistakes are essential to growth, but there is a difference between insanity (doing the same thing over and over again and expecting a different result) and training your mindset. Conventional common sense dictates we reward ourselves for working harder (expending more physical effort) in accomplishing something. In actuality, it is best to focus on hard work and strategies used.
The effects of focusing on mentally working harder, thinking more deeply, and trying different approaches to working and learning can be most clearly seen with children. Kids who are praised for being smart with the implication that success pivots on intelligence end up developing a fixed mindset. When these same kids experience struggle, they assume they were not so smart after all and lose confidence.