Things we cannot recover in life:
- the word after it is said
- the moment after it is missed and
- the time after it is gone

In this digital age, we are all used to the 'undo' button. On the computer, it is usually 'ctrl+z'.
Made a typo - undo
Cropped a little to much - undo
Chose the wrong color - undo
Pasted it in the wrong page - undo
Even internet browsers have a back button if you click the wrong link. GPS has a reroute option if you take a wrong turn. Some pages pop up a warning "Are you sure you want to.... " before the action is confirmed.
But can you do that in real life? In most situations, you can't. And the best examples of that is given in this white board image from 2014 at my workplace.
Words once spoken and heard have permanent implications. That's in a way good because that's their purpose - communication. But a badly spoken word in haste will cause unintended damage that cannot be undone. Human beings are capable of blurting out words without thinking in an emotionally charged situation. These words can hurt, wound and even destroy lives and relationships. Once said, even if forgiveness is sought afterwards, the damage does not reverse. There are still wounds and scars that remain and trust is often lost.
Moments that pass cannot be recovered. You can't wake up at 8 am and watch the sunrise. You can't reach after the plane takes off and expect to board. You can't go the next day to the examination center and hope to write the exam scheduled for yesterday. You need to be aware of when things will happen and be there at the right place at the right time. Life has its unexpected moments too. Be alert always! Or else you can miss some magical moments and events.
Time cannot be rewinded. Your childhood will never come back. After a certain age, you cannot carry your children anymore. You cannot kiss her lips after her time on earth is over. Your college friends will not be close to you forever. Make each phase of your life the best. Live to the fullest. Share as much as you can. Create memories that will last long after the moments are over.