If
I could change one thing about my life, I'd travel into the future
and fight myself.
And
when I lost that battle, I'd travel back in time to train my past
self under my future rigorous standards so I'll be tough enough
to defeat me later, not knowing that I already knew that I'd go
back to train, and thus trained my future future self twice as
hard to counter my past self.
And
when my future future self and former past but now regular future
self fought, my future future self would become the SUPREME CHAMPION,
at which time all eight of us would realize that it doesn't matter
who wins, because now we'd all eventually be SUPREME CHAMPION,
barring any further time travel altercations.
You
should read about Moon
Fountains, if only for the name.