A cardiologist was taking his car to a mechanic for a tune-up. The mechanic opened up the hood, looked around, and said, “Look at this. I take out the valves, clean ’em up, put in new spark plugs, and check the wiring, and I get thousands of dollars. But you, doc, you listen to the heart, take out a few valves, bypass a blocked artery, and you get paid millions! How is that fair?”

The cardiologist calmly smiled, patted the mechanic on the shoulder, and said, “Try doing it with the engine running.”