go back in time.
You can't go back in time... But you can send yourself a warning to the past, but this will mess up time and cause some sort of awkward mess they'll make a movie about.
Imagine if you were to change how time worked what could happen. Feral Heart could be Feral Butt, and that won't end pretty.
In short, Don't live with regret, it could have been a whole lot worse if you had done it another way.
What were we talking about again?