Blocked
Well, I decided that one of the most important words that I needed to start using instead of substituting was "thank."  I would always say "appreciate it" which usualy came out more like "preciate it" instead of "thank you."  I had practiced when I was by myself and was saying "thank you" just fine.  But when a guy held the door for me today and I tried to say "thank you" I couldn't get it out!  Nothing came out; I couldn't even get out my usual "preciate it."  I ended up just nodding my head and feeling stupid.  He didn't seem to notice, so hopefully he didn't tell anyone I had gone crazy.  I will keep trying and will never give up!