Commenting so I remember to add mine later. Can't think of one in specific at the moment, although I know I've had them (and recognized them before)

E: Got it. This isn't exactly what you asked because it hasn't totally changed my life yet, but I expect it probably will. A few weeks ago when I was on my grand college tour of the Northeast, we visited Colgate University on day 3. It had been my sister's idea to visit, so originally my mom suggested that I find a quiet place to sit and read while she and my sister did the information session and stuff, but for whatever reason I just decided to go too. I had no interest in the college prior to that day (it was filtered out of my search because College Board listed it as "rural"), but by the time we were like 5 minutes into the info session it was clear to both my sister and me that this was more my speed of school. By the end of the day, I had pretty much decided to apply early decision.

So far the choice hasn't really impacted my life beyond the college application process, but if I end up going to Colgate the next 4 years of my life (and probably a significant portion of the rest of it) will be totally different because of that one moment. Something something ButterflyEffect