I really like the answer @NofP gave.

I can add one more condition that would make it acceptable to the reader:

Forth: The character did something in the past that directly made the luck possible or probable.

Maybe the character helped someone early in the story who is responsible for the "stroke of luck." The important thing is that the MC didn't help the person expecting something in return. They helped that person because they thought it to be the right thing to do. Also, instead of a direct result, it is possible that the character did something that started a chain of events that, eventually, resulted in the character's "lucky break."

I really like the answer @NofP gave.

I can add one more condition that would make it acceptable to the reader:

Fourth: The character did something in the past that directly made the luck possible or probable.

Maybe the character helped someone early in the story who is responsible for the "stroke of luck." The important thing is that the MC didn't help the person expecting something in return. They helped that person because they thought it to be the right thing to do. Also, instead of a direct result, it is possible that the character did something that started a chain of events that, eventually, resulted in the character's "lucky break."