I do believe it all starts with how CURIOUS you are. At least that is what happened in my case.
Yes, I believed it all, I wanted to do everything they ask for BUT, I was highly curious about other things. Then this curiousity impelled me to listen to external sources, for example, I did go ahead and bought the Personal Power II tapes from Tony Robbins and listening to him, a lot of stuff came up that made me stop and think. He talks about having a purpose in life and how he and lots others have that purpose and it works for them and they are happy.
When I heard that, I knew for a fact that expresions like: " Our close relationship with Jehovah makes us the happiest people on earth. " are not necessarily true. There are people out there that use other methods to achieve the same that JWs achieve. I remember saying that if the bible was the user's manual for the human, Tony's ideas were like a service manual for humans. Then I thouhgt, but he's not inspired.
However, it required years before I allowed my curiosity to get the best of me and go onto 'apostate' websites. After the child abuse debacle and the article in the "Our Kingdom Ministry" from Sept. 2007 (I think) where the GB stated that they didn't condone people investigating and that one should NOT check on their translation work, a huge WHAT THE HELL ARE THEY TRYING TO HIDE thought popped up in my mind. My curiosity won overhand and in a couple of months I was DA'd myself.
So, I do believe that external influences help, but I also think that one has to have a level of curiosity that pushes one to want to know more.
Vivalavida