What were the most difficult classes you had to take in order to become a nurse?

That will likely be different for anyone you ask, particularly with nursing courses.

As you're just starting, I'll elaborate on what you'll encounter in the near future. The pre-requisite core sciences are often challenging and so, so important to your foundation. They were difficult, but I loved most of them and found so much of it fascinating. My advice in those courses would be to focus on your comprehension of the material, not memorizing. This trips up a lot of people because memorization is not helpful if you are not able to apply the material to anything. Also, you'll be able to recall the material much more easily if you make an effort to process it this way early on. I don't remember EVERYTHING I learned in anatomy &physiology or microbiology 3-4 years ago off the top of my head, but I am able to recover this past knowledge much more easily because I worked so hard at making sense of it. 9/10, the information should make sense to you, only 1/10 is maybe memorization.

Everything you learn will be built on later. Anatomy & physiology builds on biology and cell biology. Nursing fundamentals builds on your prerequisites, which will prepare you for med-surg, and every nursing student knows med-surg is the foundation everything else in nursing school builds on.

Best of luck to you!

One thing at a time!