Just curious were there any circumstances that caused you to get a low GPA and MCAT? Although the reason may not play a big role, it might play some small minute role in your personal statement.
In regards to your MCAT, you will need to do some deep soul searching and figure out why you got a 13, and how you are going to get a higher score. It will be rough, since on average, retaking the MCAT will only improve your score by 1-2 points. But thats an average, people have done significantly better and worse when retaking it. You will have to gauge when you are ready to take it. I don't know what your situation was when you took the MCAT, but i recommend you take practice exams (AAMC, etc) to see where you are at. If you are getting 13's one month before the real exam, I would suggest you defer to the next testing cycle. To be in a relatively OK place for MCAT scores, you will need to have AT LEAST a 15 point improvement to reach the national average of 28. Of course that is also an average, but the higher you are, the better.
Your GPA is something "easier" to deal with, since there isn't a VR section involved. Just do post-bacc. In your case, grad school, even if allowed to take upper div undergrad classes would not be a good idea. You will need to do some kind of post-bacc official or unofficial, and boost your GPA up by taking upper division science classes, and even non-science classes if you are low in that area too. Retake all classes that you got a D or F in, retaking classes that you got a C in can go either way. If you are going to apply to DO schools than that is fine, since they take the better of the two grades. While MD schools will take both classs. Be warned, MD schools will EXPECT that you get an A in these classes since retaking a course SHOULD give you an advantage. Pretty much you will need to show the adcoms that you can do about 3.5+ per quarter/semester of challenging classes at a relatively moderate to high workload. Taking 1-2 classes per semester isn't too good because they'd expect you to have plenty of time to study and do well in those classes anyway. Even those that have to work, should try to take a good balance of classes to show adcoms you can handle the workload.
Yea, its NOT IMPOSSIBLE, but I really suggest that you ask yourself, why you want to be a physician, and what can you change in your lifestyle to start churning out high GPA's and MCAT scores. I'm not trying to be mean, since it took me about 3 months of realizing what I had to do to acheive the GPA and MCAT scores I needed. I went from <3.0 as an undergrad, to a 3.4 post-bacc, and now cumulative 4.0 in grad. On my MCAT, i went from 24 to a 36. Now I just have to finish my degree before I apply to med school. Sad part is, if i don't finish my PhD in time, i'm gonna have to take the MCAT again..lol

So yea, you can jump in GPA and MCAT scores by a lot, just takes a change of attitude and discipline in your life. Hope that helps!