Why should I keep a diary of my healthcare-related activities during college?
Professional careers are by nature competitive. Professional schools and employers need certain kinds of information in order to choose the best possible person for the position, which you hope will be you.
They'll want to know: "What is your motivation for this position? Why are you suited for this position? Why do you want this position at this particular institution?" Coming up with genuine answers that set you apart from the crowd of applicants is best done with a reliable record rich in details.
There's an old saying: "Keep your diary, and your diary will keep you." A diary is a real-time record rich in details. College takes years to complete, and in that span of time, you are likely to have a variety of experiences that (consciously or unconsciously) influence the career direction(s) that interest you. Any of these experiences might serve as evidence of "why I want to do this", to "why I don't want to do that", to "I never knew this about the career".
Sample experiences include (but are not limited to):
These experiences add up to your motivation for a career, and it's that motivation that will be queried during any application or interview process. Keeping a physical record of your accumulated experiences will leave your brain free to pursue other work (like studying!), while assuring that the memories are there for you to re-examine and remember when it comes time to prepare your cover letter, personal essay, or interview. You'll have the names and phone numbers and dates of anyone who supervised you during college, when it comes time to list these on your resume or application, or ask them for the all-important Letter of Recommendation. Instead of vague stories that you struggle to recall (while nervous), you'll have vivid details to relate easily, with confidence.
Your diary needn't be a fancy little book. It could be a shoebox or large manila envelope into which you stuff papers, or a file folder in your filing cabinet. It could even be electronic, stored on a disc drive (which you will regularly back up, right?).