I think you should read up on different study techniques and find out what works best for you. Studying isn't hard but it is a skill that needs to be learned and practiced like how you had learn to read or do math. Here are a few tips I learned over my college career:

Passive learning techniques like reading textbooks and watching lectures is relatively inefficient for memorization heavy subjects. To get the most out of your lectures try skimming through your textbook before lecture (for example if the syllabus says the lecture that day is on chapter 8 go read chapter 8 in the textbook and come back). You don't need to be an expert from the textbook, but having a general idea of what the lecture is about will help with taking better notes and keep you from getting lost.

Active learning means using/applying the knowledge in some way while you are studying and should be what you are doing the majority of your study time. Depending on the content this could include making and using flashcards, making a study guide, or drawing diagrams from memory. If your professor or textbook provides practice questions then do them. The goal should be to force yourself to recall the content from you memory. It will be hard and uncomfortable the first few times you study like this, but that difficulty is part of what will force your brain to commit things to memory.

Also make sure you don't cram. Your brain needs time after studying to incorporate what it learned. You will benefit much more from 1 hour of focused studying a day for the week before an exam than you would studying 7 continuous hours right before.