all in a day's work

Definition: nothing special, part of the routine
这句话的意思是“没什么特别的，司空见惯”

例句：

Don't worry about it. It's all in a day's work.
别担心，这没什么特别的，

Cooking is all in a day's work.
烧饭是常有的事儿。

All work and no play makes Jack a dull boy.

Definition: Idiom meaning that you need to have fun in order to be a happy, healthy person
这句话就是传说中的“只工作不玩耍，聪明的孩子也变傻”。

例句：

Go home! Remember: All work and no play makes Jack a dull boy.
快回家吧，要记住：只工作不玩耍，聪明的孩子也变傻。

I'm worried about him. He hasn't yet understood that all work and no play makes jack a dull boy.
我很担心他，他还没有明白过来，只工作不玩耍，聪明的孩子也变傻。

dirty work

Definition: Necessary, but uninteresting, or difficult work
这句话的意思是“必须要做的但很无聊或很难的工作”，其实也就是做苦工，或者是吃力不讨好的工作。

例句：

He did the dirty work on that project.
他在那个项目中做的是吃力不讨好的活儿。

Have you got around to doing the dirty work yet?
你已经在找时间做这个很无聊的工作了吗？