Luck plays a role in a lot of things that happen in life. Sometimes you're the lucky winner. Sometimes you find a bright shiny penny on the ground that presumably is a sign of luck. You avoid an accident, you make the shot that wins the game. Sometimes you survive something catastrophic, and you feel "lucky to be alive."
We test our luck. We gamble, we take chances. We rely on a good luck charm; we wear our lucky shirt. Sometimes it works, sometimes it doesn't. Luck is fickle. And it's always there, deciding whether or not to jump in and favorably affect the outcome.