A mechanic was removing a cylinder head from the motor of a Harley, when he spotted a world-famous heart surgeon in his shop. The heart surgeon was waiting for the service manager to come take a look at his bike.

The mechanic shouted across the garage, "Hey Doc can I ask you a question?"

The famous surgeon, a bit surprised, walked over to the mechanic working on the motorcycle.

The mechanic straightened up, wiped his hands on a rag and asked, "So Doc, look at this engine. I also can open hearts, take valves out, fix'em, put in new parts and when I finish this will work just like a new one. So how come I get a pittance and you get the really big money, when you and I are doing basically the same work?"

The surgeon paused, smiled and leaned over, and whispered to the mechanic..... "Because I do it with the engine running!