Everyone asked a 100-year-old man and his 98-year-old wife for their health secrets. The old man said "I'll tell you my secret. I've been married for 75 years. I promised my wife when we got married that when we quarrel, the loser has to walk for 5 kilometers. So I've been walking 5 kilometers every day for past 75 years!" Everyone applauded and asked again "But how come your wife is very healthy as well?" The old man answered "That is another secret. For 75 years every single day she has been following me to make sure I really walk the full 5 kilometers!"