You have the option to go back in time and change ONE thing. Do you accept it, and if so, what do you change?

No... bc I’d be kicking myself thinking ‘why didn’t I change That!?...or That!!?... just one thing wouldn’t do it.... (the really regrettable mistake...or the other one?...the death of my father?..or my friend’s death as a teenager?...)... no, having to choose one, for me, couldn’t be done.
Thank you anyway. 😁