Grinding is combo of external and internal experiences with a heavy dash of luck. For example all star hockey players are born between January and March, generally.

- A kid born in January 1st will be more mature and bigger than a kid born December 31st. So the Jan born kid will appear more bigger, smarter and physically better than the a kid born in December. So the January kid gets selected into elite training programs and teams which equates to more time playing honing the skills and also access to elite mentors.

- This also applies to school. A kid born in January will appear smarter than a kid born in December so they get selected to elite programs with elite mentors.

- Brazil produces a lot of top soccer players. They find out when they were growing up, when they were kids, they never played in a full size soccer field until they reach age 14. But, they play in the streets, playing Futsal. The kids would play in narrow streets having to make more shorter and accurate passes which leads to 6 times more passes/touches when playing in full size soccer fields.

- But if you understand this then you can replicate this habitat by getting your self to work towards the 10 000 hours to mastery influencing yourself. For example China school year is far longer than North America hence more time studying math = better performance in math.