Does future work become easier when you study hard in school?

Or are you expected to bust your ass always, at that level, until you retire? Or die?

Wouldn’t it be better to give a natural amount of effort from beginning to retirement? That way you can be sorted into the right job/career?

Or does hard work pay off?

For example I spend hours a day Fluthering for fun, and it doesn’t seem like work even though I put more effort per day than I would all week at school. I feel rewarded for my efforts. Answering my questions helps me so the relationship is symbiotic.