A mechanic was removing a cylinder-head from the motor of a Harley motorcycle when he spotted his cardiologist – Dr. Simon Goldstein in his shop. Dr. Goldstein was there waiting for the service manager to come take a look at his bike when the mechanic shouted across the garage "Hey Doc, want to take a look at this?"
Goldstein, a bit surprised, walked over to where the mechanic was working on the motorcycle. The mechanic straightened up, wiped his hands on a rag and asked, "So Doc, look at this engine. I open its heart, take the valves out, repair any damage, and then put them back in, and when I finish, it works just like new."
"So how come I make such a small salary - and you get the really big bucks? You and I are doing basically the same work!"
Dr. Goldstein paused, smiled and leaned over, then whispered to the mechanic, ''Try doing it with the engine running."