行百里者半九十

xíng bǎi lǐ zhě bàn jiǔ shíxingbailizhebanjiushi

1. lit. ninety li is merely a half of a hundred li journey (idiom)
2. fig. the closer one is to completing a task, the tougher it gets
3. a task is not done until it's done

Study it in Yanamino