In my podcast I always end with something akin to "Stay frosty, stay in the zone, and I'll catch you all on the flip side, take care." Sometimes I wonder if the weight of those words is lost on listeners as just a long-winded "adieu". But there is something so powerful in those words that I thought it was worth expounding upon in some detail.
Without going into too much detail, I am currently in the process of doing something that I don't want to be doing. My first reaction is to just get wildly frustrated and spend most of my available energy seething and focusing on how I don't want to be doing this particular thing. Once I am able to let go of this feeling, I am able to get things done quickly and efficiently. I think the effect being fired up and having the right mindset can change the outcome of your performance in physics or anything else profoundly.
If you are a physics major, or considering dedicating your life to physics in some capacity, here is something you need to consider: if you don't love this, you probably shouldn't do it. If you're not interested enough in physics to talk about it casually, this is not the craft for you. If watching science shows on TV doesn't keep you from flipping the stations, consider a new course now.
On the other hand, if reading science magazines does get you all hot and bothered, this still may not be the path for you. But it is a sign you are on the right track. There are certain courses after the entry level stuff called screen courses. They are unbearable. That is the purpose of them. They are unnecessarily time consuming and difficult. The idea is that anyone who doesn't really have a fire for this line of work will not make it through the screen. If you can't let the material consume you and embody almost every waking moment, how will you be able to do it ad infinitum for the rest of your life? However, if this is truly for you, don't lose hope. It's ok to do terrible. You will make it through.
What will help is getting fired up and being in the zone. It can magnify your focus and stimulate your curiosity to go down dark alleys on homework assignments, and not get frustrated when the problem isn't working out. Getting finished isn't the goal. Understanding what's going on is the whole purpose. The idea is to ram the material so far into your brain that the topics are no longer forebrain fuzzy ideas. They are embedded in the fabric of your consciousness. You can talk comfortably about it with professors and other classmates because you aren't constantly re-evaluating yourself on the fly. You know this stuff.
If the material is still in your frontal lobes and not in your fish brain by the time the exams come up you are not in the position you should be in for that test. Exams that I did phenomenally well on I don't remember the majority of the test period. When I was confident I could go into auto-pilot mode and let my subconscious do the work. This is how I do my best programming. I feel like I go into a sort of coma while it's going on. I kind of just stare at the screen, or homework paper blankly and let the information flow from my fingers. This is being in the zone. This is having an understanding of what you're doing. If you have to think about it, you don't know it very well.
The time between exams is for anxiety and worrying about the next exam. It's about keeping the material in your head and letting it sink deeper and deeper into the sands of your subconscious. Only when it's buried so deep that you don't even really know it's there will you be truly prepared to move forward.