I've been doing kung fu and tai chi for 3.5 years to date which has helped my posture. I can straighten out my back when I stand, but I still collapse my shoulders forwards when I stand because it's so ingrained. I can consciously open that area up (I like to pretend that I'm Superman getting ready to fly), but eventually I want this to become more natural so that I don't have to put in as much conscious effort as I am now.
I'm a programmer by trade spending a lot of time in front of a computer, but I suspect my hunching posture also comes from some self-esteem and psychological issues from being bullied when I was younger.
What are specific things I can do to work on this area? Will lower back exercises or reversing a hunch help? How would mentality come into play in achieving my goal?