Grandpa Cartnell was celebrating his 100th birthday and everybody complimented him on how athletic and well-preserved he appeared.
"I will tell you the secret of my success," he cackled.
"My wife and I were married 75 years ago. On our wedding night, we made a solemn pledge. Whenever we had a fight, the one who was proved wrong would go outside and take a walk."
"Gentlemen, I have been walking in the open air day after day for some 75 years now."