when i was in 9th grade (before i wanted to be a doctor), i decided to volunteer at a hospital for something to do and quite honestly to help me get in to a good college. i didn't like it at first (they stuck me in medical records), but when i requested to change departments (i worked for the courier service where u deliver flowers/gifts to patients and medical supplies to all over the hospital), i really started to like it. i was only 14 and volunteered 2 hours a week for the school year (it was ~50 hrs, because of holidays and because it starts later in the school year). i couldn't volunteer the next year because i had other commitments (taking care of my little bro, etc).
when i was 16, i decided i wanted to be a doctor (by this time i had moved), so i decided to volunteer again. this hospital was pretty flexible in that you could work anywhere you wanted (didn't need to request change of department) and work any hours you wanted. i absolutely loved working there. i worked in peds, cardiac surg care unit, CT scan room, med wards, ortho center, mostly EAU (express admission unit) because it was busy and they always needed volunteers.
i didn't do anything glorious. i mostly put together charts, stocked med supplies/patients' rooms, and whatever the nurses needed to get done. but i did get direct patient contact and witnessed some suffering that has really affected me. although i had a busy school schedule (i was doing full-time college and high school at the same time), i volunteered there ~6-8 hrs a week.
i enjoyed it because i knew i was helping the staff & patients and because it reminded me every week of why i was studying so hard in school.
unfortunately, i moved back to california ~2.5 months after i started working there. so i only accummulated ~50hrs there.
so i have ~100hrs of volunteering total, which isn't much compared to most of these premeds. but both of my experiences were meaningful to me. and i hope to do some more volunteering once i transfer.