nì shuǐ
against the current
upstream
nì shuǐ xíng zhōu
lit. a boat going against the current (idiom); fig. you must work harder
xué rú nì shuǐ xíng zhōu , bù jìn zé tuì
Study is like rowing upstream: no advance is to drop back
nì shuǐ xíng zhōu , bù jìn zé tuì
like rowing a boat upstream, if you stop moving forward you fall back (idiom)