I said stop taking bullbusting courses. By this I was implying my standard advice. That is, take a reasonable schedule with a mix of courses in which you have a good chance of achieving A grades, performing research/volunteering, and keeping your sanity. At the end of the day, you must take gen chemo, orgo chem, and physics, and mostly As in these courses at a reasonable 4 year institution is typically enough to weed out who is suitable for medical school. I'll write a longer post than I have to just because of how far taken out of context I think I was taken and how annoyed I am at medical training and "academics" these days in general.
When I was an undergrad, the pre-med advisors routinely advised pre-meds to take intense schedules with the idea that medical school was so rigorous that you had to jump very high hurdles in undergrad to succeed in medical school. The advisors didn't take me seriously because I was a high school dropout without any grade school science experience, and so I just fumbled my way through this process with the help of SDN.
So many of the other pre-meds did not maintain a high GPA due to intense schedules, had little to no time for research, and wasted their time on activities like honors college essays. They would go on to take their MCAT in the spring of their Junior year with an intense schedule and bomb their MCAT. All because, "well med school will be harder than this". No, actually it isn't. So our acceptance rate to medical school from our undergraduate school was only about 60% and a big chunk of that was to DO programs.
(caveat: unlike a lot of big name places, they didn't discourage or not recommend people who applied with sub-par med school applications. When you hear a prestigious pre-med program claim 90% or whatever medical school acceptance, it's because they sabotage anyone applying who they aren't certain will get in.).
Meanwhile, I took a light schedule every semester, had plenty of time to do research, gave myself plenty of study time for the MCAT, and graduated with a 3.9. By a light schedule we're talking about 4 courses each in Spring and Fall, typically two hardcore science, and two fairly fluffy humanities courses. But you even have to be careful in the humanities. Our grades are precious. As long as US News and World Reports Research Medical School Rankings (tm and holy bible of pre-allo and medical school/hospital administration) uses undergrad GPA as a ranking criteria, you need to play that game. It's unfair that your ChemE 3.2, top 5% of their major, from a top undergrad for ChemE gets bypassed for medical school, while the 3.9 psychology major goes to top-10 medical school. But this is a game. Play it. The sooner you start taking that advice, and not listening to feel good crap like "learn what's interesting to you", the better off you'll be. If that sounds incredibly distasteful, get out of medicine, especially academic medicine, now.
I learned to play the game when I took Music 101 with a bunch of serious instrument players, where an A grade was a 95%+ and I couldn't even manage to get the A. Would I recommend a pre-med take that course? Nope. There was a history professor at my undergrad who hardly ever gave out A grades and even then it was pretty much only to history majors. So don't take that class. Conversely, there are classes with really hard sounding and interesting subjects that routinely give high grades (see most graduate school courses). I knew the developmental neuroanatomy test was going to be a joke when question #1 was "The basic cell of the nervous system is: " with a b and c choices, one of them being "neuron". But I still learned a ton and got my easy A like everyone else who bothered to show up.
Maybe this is anathema around here, but I didn't think med school basic science was that hard. My undergrad biochemistry was FAR harder than med school biochemistry. I thought anatomy compared to organic chem in the pace and intensity of memorization. Learning how to memorize useless trivia is possibly the only use for organic chemistry, which is otherwise completely useless. Our med school held back maybe 1 student out of 150 every other year. And we had the highest step 1 averages in the country. It's hardly a weed out process once you're in medical school. But, the games of grading get worse. In clinics, where the grades really matter, the grades have nothing to do with your undergrad coursework. Clerkship grades are more about how much you smile, fake enthusiasm, and kiss ass. It's all a game. But, you're thinking about academics where getting a residency is a game based on numbers and kissing ass, getting fellowship is based on numbers and kissing ass, and getting faculty positions and promotions is based on arbitrary numbers and kissing ass. So, get your numbers, kiss ass in your research lab, and move on to the next opportunity to play the game and kiss ass.