Your daughter made some bad grades on her progress report at school. You ask her why, and she complains that her homework is boring. You're annoyed that she would complain about this, so you say:
Life's not all fun and games.
This is a set expression. When someone complains about doing something difficult, boring or unpleasant, you can tell them this. The meaning of the phrase is that you can't have fun all the time; you have to work hard sometimes.
The phrase "fun and games" is used in a few other expressions as well. When they're used together like this, it's usually meant to criticize the idea of people doing things that aren't careful or serious enough:
It's all fun and games until somebody gets hurt.
I appreciate the offer, but I don't have time for fun and games. I have work to do.
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