I believe many schools use TurnItIn and this tool is excellent for spotting plagiarism. That's why I would risk. But if you believe her content is good and you do want to use some of it, you can write something like this 'my friend thinks/believes/says etc ......' but paraphrase it. I don't think it will be consider plagiarism since you credited this friend of yours and since it is paraphrased there is a 90% chance plagiarism check won't find it. But still I wouldn't recommend to base your paper solely on her content. Just use a sentence or two that would convey the thoughts and ideas of your friend. And you should always think carefully how you should use this limited space. One of my friends wrote over a thousand words and didn't even know what tp cross out. He actually used writing services. You can read
about acewriters but I'm not sure where this will get him or any other student. Anyways, I wish you good luck.
As a former ghostwriter and a current writing consultant for college and premed and occasionally residency candidates (where it really doesn't even matter), I would like to say that TurnItIn is a pain in the ass -- literally, anything that has ever been posted online will be checked against the document you turn in. It's a robot, so even if you are referencing the material you once wrote yourself, it'll turn up as "plagiarism." Nevertheless, I would say that the use of a professional editor /consultant that will help you come up with original/unique content is useful for some people if they are really struggling.
As for personal statement content, I would argue (from the mere position of self-declared "expert" with a lot of self-declared "writing experience") that many students mistakenly believe that the personal statement is equivalent to autobiography or CV. I think the personal statement has a unique role of expressing a viewpoint, philosophy, or insight about your motivations/beliefs/reasons for choosing medicine. This intangible cannot be clearly expressed anywhere else -- too many interruptions in an interview, not enough space on a CV. While experiences can highlight, accentuate, emphasize the aforementioned reasons, I don't think activities should be the focus of your statement. Seriously, I think I've heard every way that an ED doctor is inspiring by now.
So, to the OP who asked if you could write generally? Sure, but it might be more illustrative to give an example or two. That said, an example without a clear general point, is... well... pointless.
Now if someone else's thoughts -- verbatim --- are really representative of your motivations then by all means, quote and credit. However, it's kind of weak...that you can't come up with something yourself or paraphrase that idea (especially since there are only so many themes that arise and everyone ends up writing the same drivel anyway). If you plan on referencing someone else's experiences then that's super weak, since isn't part of your job acquire such experiences as a premed? Can't really say much more without knowing the specifics of this content.