Definition
This idiom is used to encourage immediate action rather than delaying it.
机不可失，时不可再
You've always wanted to learn to play the piano, so start now! There's no time like the present.
你一直想学钢琴，现在就开始吧！把握当下。
I was hesitant about taking a trip, but I realized if I don't do it now, I might not have the chance later. There's no time like the present.
我原本对旅行犹豫不决，但后来意识到如果不现在去，以后可能就没机会了。把握当下。
If you want to apply for that position, do it today! There’s no time like the present.
如果你想申请那个职位，今天就去做！把握当下。