An accountant is having a hard time sleeping...
An accountant is having a hard time sleeping and goes to see his doctor."Doctor, I just can't get to sleep at night." "Have you tried counting sheep?""That's the problem - I make a mistake and then spend three hours trying to find it."

A doctor is complaining to a mechanic
A doctor is talking to a car mechanic, "Your fee is several times more per hour then we get paid for medical care."

"Yeah, but you see, doc, you have always the same model, it hasn't changed since Adam; but we have to keep up to date with new models coming every month."