I am shy too and have plucked up the courage to stay to meetings this time round, I have found it encouraging.
Like this week was my first week and I only lost a lb which I was disappointed with, but because I stayed I heard about other peoples weight losses and it made me think 'yes, I can do this - it's worked for everyone else so must work for me too'. If I had gone straight home I think I would've gone off the rails.
Having said that, years ago I went to an early morning WW class that was just weigh and go and I lost weight consistantly on that because my head was in gear!