The only advice I can give when it comes majors has always been to do what you love. To prove a point, on my interview, my grades were of critical point. The doctor who interviewed me was a pathologist and, if my Microbiology and Parasitology grades were less than perfect, I doubt if he would’ve given me a thumbs up. It wasn’t my favorite subject and thank God I fared well, or things would’ve blown apart. Yes, schools look for diversity, but if you do love physics, then go right ahead. And remember, diversity doesn’t have to come from odd majors.
Here in the Philippines, the med schools require a certain amount of units in Physics and Math (and so on) so you should probably look into the requirements of the prospective med school you plan to apply to in the future, just so you know you’re not missing any subjects. As early as now, you should make a list of the schools you plan to go. Sometimes some med schools have different affinities for subjects, so make sure you’re aware of what they want.
I’ve read a few med student blogs here in tumblr to know enough that “med schools don’t really care what you major in”. They take both traditional minded folks and students with diversified majors equally. And if you think you need to balance your subjects out, grab some minors in non-science subjects or participate in some extracurriculars that are non-science related. I did debate and some English classes and it can help distinguish you from other applicants. Not that the ability to write poetry ups your chances, but it will make you easier to remember.
Science majors will burn you out faster, but when you get to med school, it will help things go a little smoother for you on your first year. There’s the trade off.
To sum it all up, major in whatever you wanna major in, finish those pre-med pre-reqs, and enjoy the rest of your undergrad years!