Graduate / 'suma cum lade' - MPH personal interest [4]

Here are some suggestions:
"...However, throughout my years as an undergraduate, my passion changed from becoming a doctor to wanting to do something else in the health care field. I did not know what I wanted to do for awhile, but I continued to give my studies all my effort. During my undergraduate career, I participated in organizations that were making an impact in the community. [Give an example of such organization and your involvement here] From the local to the state level, I always gave everything I did my best. I strongly agree with the quote by [name] that to give something less than your best is to sacrifice the gift. I have used this ideology to motivate me throughout my community service efforts..."

The rest of the letter looks good, aside from some minor grammatical errors. Hope I helped!