Luck is silly. Yes if you buy a lottery ticket you are just 'guessing', but if you win it's not luck, it's a bunch of variables working to your favour (is that luck btw?). I tend to see luck as something that you attribute because of your ignorance of what is going on (ie: finding money on the ground...you didn't actively seek it, but it was bound to come up in front of you, or whatever).

Fate is...it's an idea that (like God's omniscience) challenges free will. I'm not getting into that.

And I'm not even going to start with karma :D