Honestly, it's rather difficult to really understand whether you will enjoy a field while on the periphery. You can peep in and see what others think, have some vague idea and self reflect on cursory notions, but really, unless you are the individual providing the treatment and understanding the technical side of dentistry, you don't, and, most likely, won't know. I was an assistant for a few years and on reflection, there was so much I didn't know.
There are some who will love treatment planning, cutting perfect preps, making conversation with patients, and bringing out the best smile in people. Others will not handle the stresses (emotional and physical) and will just end up tolerating the job. There are aspects that make this profession difficult. Some will be talented with their hands right off the bat, others will struggle every step of the way. It's hard to predict where each of us fall on the spectrum.
We all have to jump in somewhat blindly and see where life leads us.
With that said, there were many moments that discouraged me, many moments that made enthusiastically happy, and I'm sure there will be many days with experiences in between. I don't think there was a singular "ah hah" moment, but so far I'm satisfied with my decision.