Like some of the others that have posted, it was a series of events.
I was sent to Sunday school and church when I was younger, but my immediate family was never very serious about Christianity. Still, I knew who God was, and who Jesus was, and prayed every so often, but usually just when I was in trouble or I needed something.
During this past year and a half, I did a lot of exploration of my faith, and what it meant to me. I'd make great strides, but I'd always slip back, and allow myself to be distracted.
This fall was when I really got serious. Bad things just kept happening to me: car accidents (yes, more than one), job problems, school problems, and to top it off, my friends were nowhere to be found during this time. I was alone, and I had nothing. Nothing, that is, except God. I turned to Him in full force during this time. I prayed endlessly, I studied the Bible, and I worked my way through devotionals. It wasn;t long before I realized that all the bad stuff that had happened to me was God's way of getting my attention. I couldn't get rid of the distractions in my life that were keeping from a strong relationship with Him, so He did it for me.
Things weren't necessarily perfect after that; I still found myself straying, and letting myself get distracted again. I soon learned to recognize the signs that that was happening, and I leanred how to pray my way through it. Now, my faith is stronger than ever, and so is my relationship with God!