I think making choices and taking right decision at right time fills the gap between the luck and hard work in many ways, lets take few factor involved in success(no definition here, mere perception) of an individual.
1) Hard work and smart work (already stated by OP and other replies)
2) Luck (already stated by OP and other replies)
3) Talent, now this is very tightly coupled with CHOICES we make, as suggested by vijay in his post, the decision we make define our life more then other things.
People choosing careers out of their interest/talent areas due to peer pressure, family problems, lack of confidence find hard work and luck both eluded more then usual. With each corner in your life, career, love, principles, people choose their lifes, some of them regret, some of them celebrate. I don't think its necessary to give example of RAM or SHYAM here where both were budding guitarists, RAM went for music and SHYAM for MBA and where story end with defining success as not huge pay cheques, bank balance, cars but the happiness people drive in work they do.
So, Yes, hard work, smart work, luck all are ingredients for success, but without right choices, this success will be as tasteless as feekki rabri!!