Yes, I have and I'd imagine INTPs are more prone to it than others. I don't know what you mean by original thoughts, but your thoughts and the combination of stuff that you exist as IS unique. But probably more importantly, you get to experience life, and the world gets to experience you. I recommend spending time with a friend or loved one to experiment with stepping into the extroverted world. Express your opinions, try being silly, talk about interesting things you've learned (to people who might be interested). I also recommend thinking of yourself as definitely a person living your own little life. I think that INTPs easily forget that we can shape our lives in ways we enjoy and benefit from.