I once had an english teacher in high school who would cross out entire sections from my thesis statement, and hand me back the paper with an "I don't have time to deal with this crap" stamp on it. I would go to her classroom once classes were let out, and she would tell me what the "crap" was, and I would rewrite the thesis.
Oftentimes, the paper I was going to write originally — the one that she crossed out- —was not written with much gusto, or enthusiasm. It was something that I had to do, simply because I was a high school student. However, after sitting down, crossing out everything I had written that was void of passion or interest, and discussing whatever it was that the paper was about (I directly recall it being on Cyrano de Bergerac) and beginning to re-write my thesis statement with the teacher, I suddenly cared about what I was writing about. It was like magic! To inspire a high school senior to want to write a five-page paper about a poetic swordsman and the significance of his nosein the 16th and 19th centuries takes some kind of divine intervention, so I thought, but it happened.
This teacher I owe so much to, because, while teaching me to write with gusto, imagination and skill, she simultaneously introduced me to existentialism, which I now plan on writing my thesis about.
More than that, she taught me how to cross out the crap, and work on something that I care about.
I was in my existential literature class when my friend began to rant about the point of Sartre's book, Nausea. Essentially, he came down to saying, "It sounds like Sartre is just telling me that I am doing everything wrong, and need to restart my life."
The discussion then went into how Sartre was doing just that, and I brought up my high school english teacher. We discussed how, when one reflects on their actions and what they are doing, if they don't like what they see, it is a failure. However, it is not a failure in the way that one fails a test, and the grade will remain on their report card and affect their GPA, but it's instead like that of a crossed-out thesis. The existentialist, Søren Kierkegaard, described his concept of "consolidating the personality." He discussed how, when the individual does not understand their direction, or feels torn in multiple directions when making decisions, it is a symptom of a divided personality. The wants of the individual are not clearly defined, and this brings about further internal conflict within the individual that creates distress and unhappiness.
A prime example of this came the other day: a friend of mine was at a party where they were not enjoying themselves, but felt like they had to stay because their friends were there, even though their friends were hardly giving my friend the time of day. The friend was feeling very uncomfortable, and clearly wanted to leave, but couldn't because of her internal disparity. This, especially when I started pointing out her division on the subject, made her all the more stressed. If the friend would have been able to clearly decide what it was she wanted out of the situation, the decision would have been simple, and her distress would have been dramatically smaller.
This clear definition of one's wants is a major aspect of a consolidated personality, and when one has such a consolidated personality, they are able to begin "re-writing the thesis statement" of their lives, and their wants.
Sartre wants his readers to read his work, and recreate their lives. His goal is to make the reader cross out the "crap" from their lives, and begin re-writing something that the reader actually cares about. With a Kierkegaardian consolidation of the personality, this "revision" becomes significantly easier to do, as the individual knows what it is that they want, and can actively begin pursuing it in their life.
In the same way that my english teacher could make me find a legitimate interest and desire to write about Cyrano de Bergerac's nose after discarding the disinterested paper I had tried to write, the existentialist writers want to make their readers cut out the things that they are not passionate about, but monotonously complete anyways. They push their readers to find what it is that makes the reader actively care about what they choose to do, and give meaning to their lives. These existentialists want to make you cross out the crap, re-write your "paper," and be glad you did so.