there's no such thing as a free lunch idiom saying
天下没有免费的午餐
said to emphasize that you cannot get something for nothing
"I get to travel with my job but the downside is I have to give talks." "Well, there's no such thing as a free lunch." “我这份工作可以经常去四处走走，不过坏处是我得经常作报告。”“哎呀，天下没有免费的午餐嘛。”