Easy to run downhill, much puffing to run up

Similar sayings:

Easy to know men’s faces, not their hearts Easy to know men’s faces, not their hearts
Easy to keep the castle that was never besieged Easy to keep the castle that was never besieged
Easy to enroll a thousand soldiers But, ah, one general! Easy to enroll a thousand soldiers But, ah, one general!
Water and words are easy to pour but impossible to recover Water and words are easy to pour but impossible to recover
Forethought is easy, repentance hard Forethought is easy, repentance hard

Chinese sayings and proverbs