As for me, I just kept feeling less and less proud of what I was participating in.
I had a discussion about the nazi era in Germany, where my "opponent" in the discussion claimed, that the ordinairy german did not know anything about what was going on. I objected, saying that the problem was not totally ignorance, but rather that the german people havee been brainwashed by constant propaganda, to accept the nazi policies of KZ-camps and the like. I got angry saying, that the ordinairy german would of course know, that the jewish neighbours and friends were just disappearing, their shops wrecked and themselves humiliated in public. They maybe did not know eveything that was going on, but they saw enough to be able to react. They didn't, because they were blinded.
I guess that argument just plaqued my thoughts. I started to count how many I once knew, that had been DF's through time. I got the count to 35!! I started to think more seriously about what I was actually participating in then.
Besides, I really never thought my life as the paradise they kept telling me it was....and the promissed blessings of being a long time never seemed to be fullfilled. On the contrary: the most loyal pioneers allways seemed to suffer sadness and depression. Nice depressed pioners.
What prompted me to finally leave, was my littlebrother suicide. By that time I simply could not look myself in the mirror. I thought, I may not be able to change what's done, but I can stop participating and condoning practices I thought wrong.
I started to discuss my feelings and view on things in a danish forum about religion and found out, that those thoughts of mine, that had been ridiculed inside JW, was recognized, understood and agreed upon by many others. It was NOT just me who was weird and out-of-line. Many others have thought the same, and my perception of the christian message in NT I found out was totally in line with the "normal" christian community....in Denmark.
Much to tell, but that is pretty much the way the realization happened to me.