qiān xīn wàn kǔ

千辛万苦 (千辛萬苦)

thousands of hardships

all sorts of hardships; innumerable trials and tribulations

Examples:

历尽千辛万苦
Lìjìn qiānxīnwànkǔ
go through innumerable (or untold) hardships

他幼年丧父, 母亲在千辛万苦中把他扶养成人。
Tā yòunián sàng fù, mǔqin zài qiānxīnwànkǔ zhōng bǎ tā fúyǎng chéngrén.
His father died when he was a child, and his mother brought him up amidst innumerable hardships