Imagine that you (or a fictional character you’re working with) gains access to a time machine, or could go back in time through some sort of magical effect. However, once there you’re effectively a ghost–you can watch things, but you can’t interact with them or affect their outcome. Also, you can only go back to a moment from your own life, at which you were present.
If you could choose which moment to view, what would it be? Write it through the eyes of your ghostly self.
Write an alternate version where you don’t get to choose which moment to view, but are simply thrust into the middle of a moment from your past. You could free-write a list of possible moments, good and bad, pleasant and unpleasant, to choose from before you begin.
If you want to play with this a bit, then think a little more about the concept of your time-traveling self being a “ghost”. Imagine that ghosts can in fact interact with the world in some minimal way, using some of the tropes from traditional ghost story types. Rewrite your scene (or write a new one around a new moment) taking this assumption into account.