In the movie Day Watch is an artifact called "The Chalk of Destiny". With it you can change the moments in your life when you made a life changing decision. If you could, would you?

Altering your timeline could possibly create a chain reaction. I say leave well enough alone.

I have always said no to this - although looking back there are things I would have done differently.  My life now is very good, and had I made different decisions I might not have met my husband or had this life.  In the movie, the hero still met his "true love" - now if I could be sure of that...