Usually at some point in our lives, we are faced with the decision of standing up for what we believe in, or walking away. In John UPdike's "A&P", Sammy grows as he finds himself in a position to stand up to authority. I too was faced with that particular situation some years ago when I worked at a department store. In "A&P" we learn through the theme that choices may come with consequences and, those consequences in turn work to define our character.
I think this first draft shows a lot of promise. The comment provided by #6 above is especially helpful, particularly the emphasis on needing a contrast or contrasts if that's what your teacher desires. Here's how you might tighten and refine what you've written so far:
At some point in our lives, most of us must decide whether to stand up for something we believe in or walk away. In John Updike's "A&P," Sammy matures when he must stand up to authority. I too had to confront authority when I worked at a department store, but my situation differed a bit from Sammy's. "A&P" shows that choices often have serious consequences that help to define character.
You can improve your thesis by making it shorter and too the point. I would shorten the first sentence for sure. You might also turn it into a question: Have you ever had a point in your life when you had to stand up for what you believe in? Then you can shorten your thesis.
To underscore the point that Updike's short story gives no indications of how Sammy's character will be defined, your thesis may need to end at the point of epiphany as does Updike's story. Sammy acts in defiance of adult authority and then realizes, as he stands outside the grocery store, "how hard the world was going to be." So, rather than stating that the consequences that follow choices help to define character, you may need to stay with the fact that choices made by a person bring him to the realization that his world will forever be different.
I like this introduction a lot. I think the only hesitation I have about it is that "A & P" ends with Sammy's decision and the beginnings of his realisation of the hardships he will face as a result. To prove the final bit of your introduction, you will have to draw on your own experience to expand on this section. The story gives us no concrete examples of how Sammy's decision impacted his later life.
You have chosen two interesting "narratives" to write a compare and contrast essay, and you have nicely identified a common theme. However, your first concerns should really be to think about whether or not you have met the requirements of the assignment and whether or not you have expressed an idea that encompasses the main idea that your comparison and contrast lead you to. Refinement of the writing is something that can come later.
Your statements tell the reader that there is a similarity between the story and your own experience. That is the "compare" part of a compare and contrast essay. But there is no hint of how you will develop a discussion of the differences between the two stories, yours and the protagonist's. Both you and the protagonist had a confrontation with authority. Both you and the protagonist experienced consequences. There must be some difference in the situation in order to contrast them.
In a compare and contrast essay, there needs to be an implicit or stated purpose for having examined the similarities and differences and a conclusion drawn from having done so. Otherwise, why would we ever compare and contrast anything?
Let me give you an example that I hope will clarify my comments. Suppose I were writing a compare and contrast paper on two novels. Let's look at a possible thesis statement I could write:
Both Novel A and Novel B address the blended American family, with its dysfunctionalities and its potential for happiness, but Novel B is ultimately more satisfying because of the more richly-drawn characters and the gentle humor.
Notice that my thesis statement addresses similarities and differences between the novels. This puts the reader on notice that I will be comparing and contrasting the novels. I have also "listed" the ways in which there are similarities and differences, which will help me structure the body of the essay, keep me focused, and help the reader to follow along. Notice also that the reader can see why I have compared and contrasted the novels and what conclusion I have arrived at from having done so.
Once you have a thesis statement that incorporates these elements, refinement of the writing will be much easier.
I would omit the first word. "At some point in our lives" is stronger and serves your thesis better. Would it be more descriptive to say that "Sammy matures" instead of "grows"? Eliminate the "too" - the rest of your sentence establishes that you faced a similar situation, and you could describe it as being "a similar situation" instead of "that particular situation" if you wanted. You don't need to include "through the theme"; simply state what is learned from the story. It might be smoother wording to say "that making choices results in consequences" or "choices lead to consequences". You are referring to a "turn", the time to do something, not a "tern", which is a type of bird.
You've got a good start. Just do a little refining and polishing. Good luck with the rest of your essay!