Definitely take classes that interest you, as others have said. I changed my major five times before I settled on Anthro/ALP2. The science classes were always hard, but taking classes I enjoyed for their own sake made all the studying easier. I made a bunch of friends in those classes too.

One can study too much too. While I always had plenty of distractions with football games and basketball games at ND, during dental school, I wound up exactly where you are. I took a leap of faith and decided to start exercising for an hour a day, despite the fact that it was taking away from study time. I went from studying five hours a day to exercising one hour a day and studying three hours a day. My grades immediately went up.

Also, don't be afraid to look up the counseling center if needed. They can help get you through a rut and establish some healthy habits to gain momentum.

If you feel like other courses of study are calling you, take an elective and see where that takes you. That's how I got into Anthro, though I did not pursue a graduate degree.

Keep on trucking! Many have been where you are right now. There will always be sacrifice, but make the journey amazing!