摸爬滚打

1. • to go through challenging experiences
2. • to become seasoned (in one's profession etc)

Character by character

• 摸(mō)feel with the hand
• 爬(pá)crawl
• 滚(gǔn)boil
• 打(dǎ)a semantically light, transitive verb that is combined with various grammatical objects to form compound verbs and verb-object phrases with a diverse range of meanings