别等失去时才觉得苦不堪言
[bié dĕng shī qù shí cái jué dé kŭ bù kān yán]
Don't wait until you've lost something before realizing how unbearable it is. A warning against taking important aspects of life for granted; it cautions not to realize their value only after losing them. There is an emphasis on appreciating present moments and valuing what one has, as waiting for loss can cause deep regret.