The secret of my success

Grandpa 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." he explained.

"Gentlemen," he said, "I have been walking in the open air day after day for some 75 years now."