This is pretty simple, really.
Things happen to you, whether good, neutral or just plain bad.
If you live your life a certain way and are guided by core values that place you in *positive* environments, then I truly believe that when things happen, they will be generally good. At least, more good than bad. You can then say that you are a lucky person
If you go to Tijuana this weekend and hang out at 3AM in a drug infested neighborhood, I think you're going to have some pretty bad luck.
If you fly to Monaco during the F1 weekend and stay at the casino hotel and watch the race while sipping bubbly, I think you're going to have pretty good luck.