The first time somebody made me "use my brain", was in 1994.
I traveled to NJ for a seminar, and I started talking about the bible with a guy that I met there. He asked me if I was "saved". I borrowed his bible (he had a copy of a Reina-Valera version), and I showed him some specific verses I knew from James, about "faith without works is dead". I thought that I was teaching him about the bible!!! :) He grabbed it, and then showed me dozens of verses from Romans, that showed me that Faith was more important! Then, I started noticing that I didn't knew about the bible as much as I thought...and started reading the context!
As a good WT member, I suppressed all my doubts for years, even when I saw discrepancies between what the WT says vs. the instructions I received as an Elder.
In the beginning of 2007, I started doing a reserch of information for a travel to Europe. I don't know why, I started researching about Jerusalem in Wikipedia, and I noticed the destruction of Jerusalem's date of 587BC by Babylon. I started researching every book and encyclopedia that I found for weeks... The 607BC date had no base, so the 1914, 1918, 1935... all is a fairy tale...
The rest is history...