活在当下英语可以说为 "live in the present" 或者 "be present"。这个说法来源于佛教哲学，强调人们应该放下过去和未来，把注意力和精力放在当前的时刻和当前的活动上。例句：

It's important to live in the present and not worry too much about the future.

If you want to be happy, you have to learn to be present and enjoy the moment.

活在当下的英文例句及其中文翻译：

It's important to live in the present and not worry too much about the future. (重要的是活在当下，而不是过多担心未来。)

If you want to be happy, you have to learn to be present and enjoy the moment. (如果你想幸福，就必须学会活在当下，享受当下。)