What do you think is the best job on earth?

Every job is a best job in the world.
But for making any job as a best job you should generate the interest in the job and consider it as your own work.
One should always have positive energy towards the job with positive thinking and should enjoy the work. 
I have seen a lift operator, whoes job was just taking the pessengers to various floors.
But I have seen lot of positive attitude in his work.
He was always cheerful and making his best effort to reduce the time of travels.
At the same time he was always in pleasing mode, which is a requirement for lift operator job. 
 

In which I feel contented and having some sense of achievement. For me the best job is one in which my contribution makes some difference.