Talent: what you were born with. Not in your control.
Fortune: luck, chance encounters, random occurrences. Not in your control.
Effort: how hard you work. In your control.
Your talent and your luck are out of your hands.
Might as well put all energy into your effort.
It doesn’t improve your talent, but it lets you use it more effectively.
It doesn’t improve your luck, but it enables you to capitalize on the luck you do have.