Doubts about academic performance, particularly in calculus, are common among students. The discussion emphasizes that a C in calculus isn't the end of the world; understanding the material is more critical than the grade itself. Many participants share experiences of overcoming initial struggles in math and succeeding later without retaking courses. The focus should be on grasping the underlying concepts of integration and series, as these will be foundational for more advanced topics. It's noted that practical application often relies more on intuition than memorization of complex formulas. Stress and burnout from multiple exams can impact performance, leading to mistakes and decreased confidence. Strategies for improvement include reviewing material, managing stress, and developing effective study habits. Ultimately, the conversation suggests that students should assess their understanding of calculus concepts rather than fixate solely on grades, especially when planning for future courses and potential graduate studies.