When it comes to Calculus most people get traumatized due to the excessive rigor and abstraction many teachers/books start with in the beginning. There is the Heine discrete sequence approach that is far easier to understand (see https://news.ycombinator.com/item?id=49312120) than the standard epsilon-delta definition but for some reason it is not emphasized. Add the fact that many mindlessly recommend Spivak/Apostol etc. books which are highly rigorous and a beginning student is lost and starts to develop an aversion to the subject.
For some motivation see Everyday Calculus: Discovering the Hidden Math All around Us by Oscar Fernandez - https://press.princeton.edu/books/paperback/9780691175751/ev...