kǔ xīn
painstaking effort
to take a lot of trouble
laborious at pains
kǔ xīn jīng yíng
to build up an enterprise through painstaking efforts
shà fèi kǔ xīn
to take a lot of trouble (idiom); painstaking
at the cost of a lot of effort
kǔ xīn gū yì
to make painstaking efforts (idiom); after much trouble
to work hard at sth
Huáng tiān bù fù kǔ xīn rén
Heaven will not disappoint the person who tries (idiom). If you try hard, you're bound to succeed eventually.