[wàng zì fěi bó]
improperly belittle oneself; inferiority complex; look down upon oneself; think lightly of oneself; underestimate oneself; underestimate one's own capabilities; undervalue oneself; unduly humble oneself
We must be realistic in our self-estimation, neither being conceited nor belittling ourselves.
我们对自己的估计应该实事求是， 不要自高自大， 也不要妄自菲薄。