An 80-year-old man was having an annual physical.

As the doctor listened to his heart with the stethoscope, he began to mutter, "Uh-oh."

The man asked the doctor, "What's the problem?"

"Well," said the doctor, "you have a serious heart murmur. Do you smoke?"

"No," replied the man.

"Do you drink in excess?"

"No." replied the man.

"Do you have a sex life?"

"Yes, I do!"

"Well," said the doctor, "I'm afraid that with this heart murmur, you'll have to give up half your sex life."

Perplexed, the old man said, "Which half -- the looking or the thinking?"