Time.

 Time never waits for you so live your present instead of regretting about the past and worrying about your future.

Time never waits for you so spend time with your closed ones because you never know who passes away.

Time never waits for you so make good memories instead of your wasting time in arguing with someone. 

Time never waits for you so love everyone because you never know when you pass away. 

                                                       -Shriya.