One of my main goals in my medical career (if I get in...) is to volunteer for MSF (Médecins Sans Frontières). That would obviously take place well into my career so is it suitable to mention it in my personal statement, or is it irrelevent?
If you can talk about it in interview, and genuinely know what it involves, how tough it can be and the selection process etc, then it might be worth a mention. But personally I'd reckon it could trip you up more than it would help you.