Eternally confused!

Why is that when you seem to have achieved more than you wanted in life...suddenly everything seems so meaningles...we still remain restless and there seems to be a lack of purpose. The last one year at IIMA and my previous education at IIT, DPS Bokaro and GBRC bodh gaya....everything was almost perfect...better than I had dreamt of considering the kind of environment I have grown up in.. and still today I don't relish them. I am proud of my academic credentials...but I still feel I have not done enough. And that makes me unhappy...Life in second year at IIMA gives u enough time to reflect on your past and help you prepare emotionally and psychologically for the tough road ahead. And somehow I have started appreciating the contrasting life styles of fucchadom and tuchhadom at IIMA... not because I am now a tuchha but bcoz as a tuchha and having had slight experience of the work life and probably having a more realistic expectations of my future and of my family from me, I can chart a journey of my own. Last one year has been a roller coaster period for me. It has definitely helped me realize my limitations as a person and respect finer things in life.
Surprisingly, when I am at a time when I am least insecure about my future, I am also most confused about myself. I don't know what I am passionate about, what excites me, what will keep me going for 40 years of my professional life...and that is what bothers me every moment and keeps me awake till early morning!