Is sex work?

A British Army Major was about to start the morning briefing to all of his staff.
While waiting for the coffee machine to finish its brewing, the Major decided to pose a question
to all assembled. He explained that his wife had been a bit frisky the night before, and therefore
he failed to get his usual amount of sound sleep.
He posed the question ; "How much of the act of sex is "work," and how much is "pure pleasure" ?
A Captain chimed in with a 75-25% in favour of 'work'.
A Lieutenant said it was probably about 50-50%.
A Warrant-Officer responded with a 25-75% in favour of 'pleasure', depending upon his state of
inebriation at the time.
There being no consensus, the Major turned to the Private who was in charge of making the coffee.
What was HIS opinion ?
Without any hesitation, the young Private responded, "Sir, it has to be 100% pleasure, Sir."
The Major, a little surprised as you might guess, said "And why is that soldier" ?
"Sir - well Sir, if there was any work involved, the officers would have me doing it for them, Sir".
The room fell silent.