Realize that you control your own fate. If you decide to take this course you should realize that it will take much time and hard work. Don't make excuses and don't give up on a course unless you know you are going to drop it. Either one is self-destructive and won't make the situation any better. A little extra time put in early on will save you a lot of time and frustration later.
Subsequent chapters build on previous chapters and it becomes impossible to memorize everything.
A good understanding of the concepts will eliminate much of the memorization.