Oh man! Good question. As a small child, I biked around my neighborhood with friends but soon lost interest when I started driving. I regained my love for bikes in college.
For me it was probably when my cousin got a used Schwinn Continental around 2009. We were both in college and living together at the time. It was the first time I rode a bike with drop bar and I felt supremely cool. After he moved out, I searched for my own drop bar bike and found an attractive Raleigh Technium; however, the seller sold it one hour before our agreed upon meeting time.
Disheartened, I walked home. Not twenty minutes later, my cousin calls and asks if I've ever heard of Peugeot. I told him to my limited knowledge, they are well regarded bikes and he quickly hung up only to come riding down the street on a Peugeot P6. He gave it to me as a gift. That was my first "real" bike. A few years later, I gave the frame and some parts to a friend who had fallen on hard times, after it had gone through several iterations. I was on a Miyata 1000 at the time.