What is satisfaction ?

These days as I have more time on my hands, I have been trying to figure out what is satisfaction?. I know you might say that its the feeling you get when you have done something succesfully. Or as the dictionary puts it "it is the fulfillment or gratification of a desire or a need". But then I start to wonder are we really ever satisfied with what we do ?.
I remember when I was a kid in school, getting good grades and being the teachers favourite student gave me great satisfaction. But then I would always feel why didn't I get more marks than the other guy? As I grew up doing good in sports made me feel happy and satisfied. Then I thought getting a good job and earning enough money was what would make me feel satisfied. But now as I think about it I feel that I was wrong. I have a good enough job and am earning more than I'd ever thought I'll do, but satisfaction still eludes me. I feel an emptiness a void in my life. I guess I always thought of satisfaction in terms of material things, worldly things. I never tried to satisfy the yearnings of my soul. Sometimes people say that contentment is synonymous to lack of ambition. But now I have come to realise how great a virtue it is. The day we learn how to be happy and content with what we have, and try and find joy in all the small things in life. We will have sown the seeds of true satisfaction in our hearts.
I know you might say that satisfaction has different meanings for different people. But whatever little time I have spend on this earth, has made me realise that unless we don't listen to our heart and soul we will never know the true meaning of satisfaction.