At a class meeting, the teacher asked everyone: what should be the mentality of success? Zheng Lei said: it's never too old to work hard and learn. Liu Lian said: you should maintain a contented mentality and affirm your achievements. the teacher said: your views are good and only when combined can they be accurate: the mentality of success should not only work hard, but also be content.
According to the teacher, which of the followings can't be introduced?
The mentality of continuous effort is as important as that of contentment