Go through the mill:
To have a lot of problems or difficulties.
“Go through the mill” 的意思是 “历经辛苦，饱受磨炼”。某人把另一个人 “put through the mill” 是指 “让这个人吃尽苦头、饱受折磨”。
例句
I have really had to go through the mill to get this promotion – it was tough, but I got it.
我历尽千辛万苦才得到这次升职机会。虽然很艰难，但我成功了。
With my illness and losing my job, I feel I have been through the mill.
由于生病和失去工作，我觉得自己吃尽了苦头。
My trainer put me through the mill by making me run non-stop for two hours!
我的教练把我折磨坏了，让我连续不停地跑了两个小时！
