After mechanics, it’s not going to get any easier. So before you try to take the class again, you should, like lenocturne said, reevaluate your talents and interest. If you’re still truly set on engineering, then prepare to give physics your all. Physics is all about understanding the concepts. So if you’re ever stuck, really think the problem through or ask someone. Don’t be content with just getting the answer; make it your priority to understand what’s going on.