Not With a Bang

When you die, and your heart slows down and lungs exhaling that last breath, it is believed that you have seven minutes of brain activity left inside you. In those seven minutes you experience your life all over again, the good and the bad, in kind of a dream... because in a dream, time is stretched, and hours and hours in a dream only ends up as mere seconds once you open your eyes. But you don't open your eyes again after these seven minutes.

If that's all real, what if, right now you're in those seven minutes of brain activity that you have left. How is it that you know if you really are alive, or just reliving old memories.
_{titles come from T.S. Eliot's The Hollow Men.}