how can ones memory influence what one does

Certainly our memories influence who we are and everything we do. Without digressing too much, there is a sci-fi book called "Do androids Dream of Electric Sheep by Phillip K Dick. In that story androids simply go crazy because they have no memories; their emotions are unregulated so they can't function. Our emotions are regulated but only by our past experiences (memories). If you got badly bitten by a big dog as a child, you might avoid big dogs as an adult. Scrooge is put in touch with the memories he tried so hard to block out. When he accepted them, he was able to begin to change.