有人说,幸福是一种感觉,不知足永不会幸福,因此要学会“知足常乐”。“知足常乐”,汉语成语,意思是知道满足,就总是快乐(A man who is contented will be happy),形容对已经取得的成就感到满足并取得快乐。与英文谚语“a contented mind is a perpetual feast”意思相近,表示“If you are mentally at peace, you will always feel that you have enough of everything, and will not have to strive to get more”。