Whether we accept it or not, luck plays a huge part in our life. My hypothesis is that religion was invented to ease humans to accept this reality of life. Faith in a higher power or "everything happens for the good" is nothing but a means of accepting that there are things in this world beyond our control, which we can do nothing about. There's so much randomness in this world, and so little in our control. We might not like to believe this, but we are helpless against most of the things that this world has to throw at us. We can be best prepared, we can fight to our fullest capabilities, but still lose. I guess humans inclined not to believe that little is under our control, maybe wired so, or else we wouldn't have even tried. I am not suggesting that we should give up saying "Whatever I do, it's all destiny." I don't mean that. What I am saying is that we should have the wisdom to understand the limitations of our influence and realize that the randomness of this world plays a major role in our lives. And I say be aware, because that would eliminate the need for looking for answers to questions which do not have an answer other than those invented by us in the form of God et al.
By the way, I digressed a lot from what I had intended to say in the first paragraph itself. Speaks volumes about my abilities as a writer. All I intended to say was that luck (or randomness; I prefer to use randomness but luck is easier to understand and associate with) plays a huge role in our lives. Meeting the right one, let alone "The One" is as much a matter of chance as can be. You might be married for 30 years and then meet someone who you know would have been the one. All you can feel is "What if I had met her earlier..." and you can do nothing about it. And trust me your partner can make or especially break your life.
What you do defines you. And how well you do it, how good you are at it, and how happy you are doing it determines the quality of life. You can work as hard as you can, but if you don't have the aptitude for it, you will never be great at it. You will always be struck in mediocrity and you will just resent yourself, or the choices you made that led you there. Putting it simply, everyone has 'that one thing' he is made for, be it being a cricketer or a teacher or just about anything. Something he knows he was born for, and doing it is the easiest thing in the world and yet you are good at it. You can look at Sachin or Zidane and know they were born to be a cricketer and a footballer. No matter how hard they tried, they could have never become a scientist. I guess the luckiest a man can get is finding that 'one thing', and finding it young, and having the opportunity to pursue it.
If you have found luck in these two things, rest assured you don't need anymore luck. Having it wouldn't hurt, though. If only I could get just as lucky with finding my thing as I did with finding my 'the one'...