I think luck is the sense to recognize an opportunity and
I don't believe in luck. Those people who have succeeded in life usually have done so as the result of hard work, of being able to see opportunities when they've come up, or a combination of the two. Those people who win tons of money in lotteries or inherit vast fortunes aren't necessarily lucky--many people who have come into money that way have become quite miserable, very unhappy with their "new" lives.
My biggest problems in life have come when I haven't recognized opportunities. Because I haven't seen them until too late so often, I haven't been able to take advantage of them. I suppose many people would say that I've had bad luck, but I don't see it that way at all. I see it as having missed opportunities, and I don't get down on myself for having missed them. After all, there was no one around when I was growing up to teach me to recognize and take advantage of opportunities.
Most of us are in that same boat--we haven't been taught how to recognize the opportunities that come our way as opportunities, so we squander chance after chance to make more of ourselves or improve our lives or lifestyles. That's okay, because that's how life is--what's not okay is to recognize the problem and not do anything about it.
Now that I know how many opportunities I've let go by, it's up to me to teach myself how to recognize them and take advantage of them. And the burden isn't completely on me--there are plenty of books and tape programs out there that can help us to learn to do these things. This is material that should be taught in schools, but it isn't, so we have to find other teachers outside of the classroom who have focused on this sort of thing as their own area of expertise.
Bad luck? Sorry, but there's no such thing. The universe functions too well for that to be true. Sometimes it's true that things are completely out of our control, but even if something negative happens to us, there will be something important for us to learn in it. If we can smile at our bad breaks and move on with our lives, learning in the process, life becomes much brighter. Bad luck tends to be an excuse for not wanting to look deeper.