What’s happened in the Past is important, but it doesn’t exist.
You cannot actually go back and have that conversation again in a different way, redo or undo any action.
What’s going to happen in the Future doesn’t exist either.
And while the Future is worth considering, to a degree, to spend a lot of time there, mulling, wondering, hypothesizing, is all essentially in a land of make-believe; a fiction which may or may not occur.
What does exist is Now.
Interestingly, allowing yourself to be stuck in either the Past or Future is the only way to miss Now.
The paradox is that if you miss too much of Now, you aren’t really paying any respect to the Past, and you’ve given up your only chance at shaping the Future.