Are you doing the best you can and everything you can (and I don't really need to know your answer)? If so, there's no shame in that then. Not everyone is going to be good at everything and the only thing you can do is try your best.
But outside of what 2015 and others have said, classes that you dislike also teach you the valuable skill in doing you best even if you don't like the subject/job. Because there are going to be classes in college that you don't like or parts of your job you don't like. No one's going to care that it doesn't interest you, or you don't like that part, you still have to do well.