It was Grandpa Jones' 100th birthday and he was still in perfect health. At his birthday party he was asked how he managed to live so long and stay so fit. He explained "I put my long life down to spending so much time out of doors. I've been in the open air, day after day, rain or shine, for the last 75th years." "How do you manage to keep up such a rigorous fitness regime?" we asked. "It's simple" he said. "When I married my wife 75 years ago, we both made solemn pledge on our wedding night. We agreed that whenever we ever had a fight, whoever was proved wrong would go outside and take long walk."