Well, honestly I don't express myself in actual life very well. But when I type, I'm able to get everything flowing and I can identify how I feel and what I'm thinking. See, I dont know about other ISFP's, but I know I'm not very quick with the come backs and such. I need to be able to think about what I need to say before I say it. I know when someone is crying, I'll try to console them and help them, but that doesn't mean I'm going to cry. If I feel really moved by the situation, then I will. But if someone else is upset, I'm just there to lend an ear and to comfort them and to make them laugh.
Honestly, I can identify with the 'shield'. I have no idea why I do this, but every time I get around memebers of the opposite sex, I tend to 'toughen up'. Like nothing you say cant hurt me and I'm tough. When in reality, I'm really the most vulnerable and I hurt easily.
Those are just somethings to take into account.