At any given moment, it is your past being lived, as you will soon see and realize. Just wait a few minutes.
Who says you can't change you're past...you know? To change your past, all you need to do is do something at the moment and 5 minutes later you'll see the result of having changed your past. Get it?.
Being aware of this fact can really make your life interesting once you've grasped the idea .
So don't ever think you can't change your past. You're living it right now. It proves itself in just a few minutes.
