The old statement, 'Time Waits for No Man' is an absolute. No matter if you are working, waiting or sleeping the seconds tick by.
Missed opportunities never return. There MAY or MAY NOT be new similar opportunities that come up, but the same one you missed will NEVER return.
Anyway like Charlie, something missed, in reference to time, is gone forever. The exact water running under a bridge will never be seen there again, it is on down stream.
A lesson I learned at six year of age. We lived in Burington, NC and had traveled to Shelby, NC to see my brothers and sister who lived there. The road went within 3 miles of where dad's mama lived. I remember like it was yesterday dad saying as we drove by the turn off to Granny's house, "I should go by and see mama, but we will stop next time."
When we arrived home the phone was ringing, it was dad's youngest brother, "Frank, mama is dying you need to get here as soon as possible, to see her alive."
Of course we drove back immediately, but daddy never forgave himself for missing that opportunity.
That was 71 years ago and I still remember it. I have tried to follow my instincts, if I feel I should say or do something, I still try to do it.
If your inner person says, 'maybe you need to do/say-------' give it every consideration, it might be important to you or someone else.