In which you could shift your consciousness directly back to a prior point in your own timeline and change your action/decision.
Sans the brain bleeds, how much fun would that be? You would never have to second-guess a decision or an impulse - just do it and if you don't like the result, you scoot back a few minutes and undo it. You could apply this to career choices, relationship choices, every exam you ever took in school.
Sign me up.