Apptitude!

Sometimes, the problem is not that you aren't trying hard enough--it's that you're continuing to stubbornly do the old things that aren't working and expecting that somehow they will work this time. Successful people do not fail any less often than people who are not successful, but successful people do keep trying to get the job done and come at the problem again from another angle. If you're finding that you are not doing well in a class, or on the MCAT, or whatever, the solution is to stop, think about what you're doing wrong, and try something else until you find a method that works. Assuming you are of normal or better intelligence, you are intellectually capable of becoming a physician. You do not have to be a genius to get through college or medical school, but you do have to be willing to work hard.

Here's my personal example: My first semester of college didn't get off to a great start. Halfway through, I failed both my linear algebra and physics midterms. The physics prof was this sexist old guy from Eastern Europe who told me that maybe I just didn't have the aptitude for physics. After that, I started changing how I studied for those classes and getting tutored when I needed help. In the end, I passed them both. The next semester, I did very well in physics II, and I was the top student in my calc II class. The physics II prof even tried to convince me to take one of his advanced physics courses. Did I get any smarter over the course of one semester? No. I figured out what I had to do to learn the material and do well in these classes, and I didn't give up after the initial setbacks. And you know, once I started doing well, it didn't even matter any more that I had flunked those two midterms my first semester.