Public Speaking
I used to think that having done public speaking via the Ministry School was a good thing but I've since come to realize that the skills I gained are only good if someone else supplies the materials to be used and I'm speaking to an audience that is already in agreement with everything I'm going to say.
It's quite another matter to speak publically about ones own thoughts and have them questioned or challenged by those who are listening, especially if you've been "spoiled" by never having to express your own thoughts or have never had them challenged or questioned.
Keeping your eye simple
I do think that the idea of keeping a "simple eye" in terms of materialism and debt, has been beneficial to me but JW's weren't the first and only ones to realize that if you live a life free of materialism and stay out of debt, things will be easier for you in the long run.