I agree with NMC for the most part. There's no one right way of doing it, and your PS allows for a ton of flexibility. Unlike NMC, I began two of my paragraphs with things that made an impact on me while shadowing and did entire paragraphs painting the picture as to why those were significant for me, with examples of my activities/interest/future plans.
I shadowed a general dentist and periodontist, but only mentioned the general dentist.