One of the most compelling life lessons that comes out of Before I Fall is the idea that we have to atone for our cruelty. Samantha has been cruel to so many people. The most hurtful of her actions are towards Juliet. She relives Friday, February 12 as a way to make right that which she has made wrong. Her cruelty and the cruelty of her friends are what she ends up changing as the novel progresses towards its end. Once she recognizes what she has to do, Sam's epiphany defines the arc of her characterization: "It feels like I’ve reached back in time and corrected something. I haven’t felt so alive, so capable of doing things, in I don’t know how long." The life lesson here is that while human beings have the capacity to destroy, there is also the hope for restoration. The ability to make right that which is wrong provides the essence for us feeling "alive."
Like Samantha, we have to understand the need for taking action to "correct" our cruel actions of the past. This becomes one of the life lessons of the novel. At the end of the novel Sam recognizes that her life would have been much better had she not participated in the actions of wonton cruelty. The fact that she spends so much time undoing what she had a hand in creating is a part of the painful life lesson that ties up the novel. Thus one of the most potent life lessons of the novel is that we must acknowledge our acts of cruelty and actively try to correct that which is wrong.