The past comes up at random times in our lives. We cannot allow the past to influence our future, what happens in the past should stay in the past. If we allow our past to interfere with our present, our present would be a total chaos.
Think about what you have been through in the past. The relationships you were in, the friends that you had, the people that influenced you or pressured you to do something. Now think what would happen if all of that pops up again, randomly, in your life. How would you be able to cope with it? Can you?
We cannot let what happened yesterday derive us from living out tomorrow. We often try to bring back the past, if you decided to close that door of yesterday then why try to bring it back through a closed door. That is like trying to travel back in time or the clock going counter clockwise. You cannot reverse the time to relive a certain time in the past or bring forth whatever it is.
The past is the past, God removed you from yesterday so you can walk into tomorrow. Be glad that you left everything that did not belong in your life in the past. Of course the past will still be all around you watching you but it is your job to make sure that the past stays in the past.