Lol yeah I'm pretty much the same. I try to keep slim shoes for everyday wear but I need boots for any rocky hiking. The only rough part left on my foot is my heel.

True dat

Does anyone have an actual explanation for this? or is this a confirmation of super soldiers lol.

I mean honestly this is the answer. I used to long board barefoot as a teenager and I also ran track. Often ran barefoot. By the time I was 16 I could walk on some glass without bleeding.

One option is trade offs. Tell her if she study's for an hour, you'll do something she likes. That sometimes works for me.

The other option is to just be as gentle as possible, bring it up in a joke(risky). If she's just trying to get motivated, tell her about all the cool things she'll be able to do or become once she finishes classes, while telling her to study.

All this being said if she is just content with getting a C or B in the class and is confident in her current knowledge to get that, then maybe just let it be.