I was an ER Tech (volunteered 500+ hours) at three hospitals. I got to do everything an employed tech does (take vitals, clean wounds, restrain patients, transport patients, etc.). I also interpreted (Spanish-English) as a tech and as a part-time job.
When they asked my why I want to be a doctor at my interviews, I was able to draw on these experiences to share with them. I have seen the effects of suicides (hanged themselves or shot themselves in the head), homicides, stabbings, etc. Each of these experiences really helped me learn about medicine and the limitations that one will have as a physician.
I also worked for two years as a firefighter/first responder and drew on those experiences as well.
It is this exposure as an ER Tech, firefighter/first responder, and interpreter that reaffirmed my decision to become a physician. If I were on the admissions committee, I would want to be sure that the student knows what he/she is getting into, and there are several people who may have high MCATs and GPAs, but if there is no experience, then those people may struggle to get into medical school.