Leave your luck to koi fish. You just have to work hard. What does this sentence mean?

It means: do your best to complete your duties, and success depends on God's will.

God's will refers to God's will (an entity representing nature), which means that people can see and do what God has scheduled. Therefore, God's will is not considered to be interventionist, and people can only follow God's will.

It is often said in the world, "Do your best and listen to your destiny". From the sixth chapter of Li Ruzhen's Mirror Flower Garden in Qing Dynasty: "Listen to destiny". There are too many variables in the laws of nature, and the result is unpredictable. If you try your best to do something, your success depends on nature.

Life is short, if you want to realize the value of life, you must do your duty well. A person's life is a life of struggle, and the result is only second.