Time travel?

I came across something online discussing the afterlife. One man was declared dead for 20 mins and started breathing again on his own. When he woke up he described a place that could only be explained as his judgment day. He spoke of having to be with a powerful presence and was shown his life. Every single moment. Before they could finish reviewing his life in its entirety, he was filled with the sensation that it wasn't his time and he had changes to make.

It got me thinking. If there was the ability to go back, forward or pause at a certain event what would you do? Would you change anything?