Depends on what you are doing. Learning object oriented language and oop design patterns is easy. If you want to get a degree in cs you will end up having to learn math proofs, graph theory, combinatorics, probability, linear algebra and calculus. It will be by far harder than anyting you learned in highschool. You will need to know things like: sudoku backtracking, nquens problem, merge sort, how to reverse a linked list recursively etc... Programming is usually hard when you cant solve math problem. I was in the group of 75 people, only 22 made it to second year.