Is it normal to be lazy on studying?

I have set my goals straight. I want to go to Nursing school. Im currently an upgrading student and Im taking it online so its basically like home schooled. My problem is I always lack motivation on continuing. Sometimes Im on the mood and get good grades, but MOST of the time (about 80% of the time) I do nothing but play on my phone, sleep on my bed, watch tv or hang out with my bf! i need help! is anyone like this? am i normal???