There are no shortcuts to true excellence.
As our knees and hips and eyesight deteriorate, we become more dependable, less impulsive, kinder, and less moody. Psychologists call this the maturity principle. My own life experience fits this principle to a T.
Gritty people train at the edge of their comfort zone. They zero in on one narrow aspect of their performance and set a stretch goal to improve it.
Grittier students are more likely to earn their diplomas; grittier teachers are more effective in the classroom. Grittier soldiers are more likely to complete their training, and grittier salespeople are more likely to keep their jobs. The more challenging the domain, the more grit seems to matter.
Grit is living life like it's a marathon, not a sprint.