The reality is that you don't need motivation to study. You need persistence.
You didn't get into medical school because you can't. But you certainly can leave, prematurely, because you don't.
Sometimes, you need to kick your own a** into gear, whether you like it or not. It's like having to go to work, or eat healthy: we often don't do it because we want to. We do it because the alternative leaves us screwed. We have no viable alternative option (if you want to become a physician). Nobody in your class (okay, mostly nobody) wants to study like hell right now for exams after that break. That's fine, you don't have to want to. You just have to do it.
Some people say "Fake it until you make it". For others, who say "Yeah, but I can't lie and tell myself that I really like this; I'm lazy", that's fine. Everybody's different. Don't lie to yourself. Be honest. Let yourself know you don't want to. You might feel less silly, and a bit more honest. "I hate this, and I have to do this." Don't use the word "but", as in, "I hate this, but I have to do it." That breeds hesitance, and automatically irritates you. You hate this, and you have to do it anyway. You're a medical student, not a high-schooler or undergraduate. You still may feel like they do, sure. We all do. You're not suddenly a different person now, but instead, the difference is that you have no excuse, and as an adult, cannot afford to not do it.
Tough love, my friend. Tough love.