Why do we crib still?

Why do we crib in spite of having been blessed with so many things in life...why are we so dissatisfied in life often.Look at this young man who was born with no limbs and still having smile and hope to share with the world.Nick Vujicic from Australia has no complaints about his imperfections,but has sought perfection in his own way and serving God with even more ardent devotion.Nick,a motivational speaker himself, is now an inspiration for many... and believes strongly that in all things God works for the best for those who love Him....In spite of having achieved so much in life,we still sit before God cribbing...why only me?...why does it happen to me always?....why are u so unmerciful(Karuna cheivan thamasamenthe kanna....)unheedful of the sufferings of many in this world...We are less grateful to God for most of the blessings that he has showered on us...Nick is indeed a reminder for all of us...Never take life for granted!