Unwanted Work !!!

Has it ever happened to you that you have to do the task you don't feel like doing or don't have interest in. It's frustrating isn't ? Well currently I'm in the same scenario. I have to read and score marks in subjects in which I don't have a single interest. Why is it so? I tried asking my friends and teachers about it but no one has any clue. They are just doing taught what's been told earlier....