Also, since you're not applying until next year, I'm going to suggest something that I don't think anyone else here has mentioned yet: consider holding off on getting the letter from your professor for a couple of months and instead drop in a few times and have some conversations with him (or her). I was actually really pleasantly surprised at how willing a lot of my professors were to give me advice on medicine, career choices, classes to take, things to do, etc.
The feasibility of this will obviously depend on how nice your professor is, but I really do think it's worth trying. I mean, not only is it great to have a letter that says something beyond "so-and-so seems smart, motivated, and performed well in my classes," but it actually is pretty cool to get to know a professor outside of class -- it turns out that a lot of them are actually pretty normal people! Who knew?